композитор установить opentok php sdk

Я пытаюсь установить php opentok SDK через композитор. Я получаю ошибки.

Ниже приведены мои команды.

Ниже приведены команды, используемые для установки.

 curl -sS https://getcomposer.org/installer | php
php composer.phar require opentok/opentok 2.4.x

Выход:

./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

Problem 1
- The requested package opentok/opentok No version set (parsed as 1.0.0) is satisfiable by opentok/opentok[No version set (parsed as 1.0.0)] but these conflict with your requirements or minimum-stability.
Problem 2
- Conclusion: don't install sebastian/version 1.0.6
- Conclusion: don't install phpunit/phpunit 4.8.35
- Conclusion: don't install phpunit/phpunit 4.8.34
- Conclusion: don't install phpunit/phpunit 4.8.33
- Conclusion: don't install phpunit/phpunit 4.8.32
- Conclusion: don't install phpunit/phpunit 4.8.31
- Conclusion: don't install phpunit/phpunit 4.8.30
- Conclusion: don't install phpunit/phpunit 4.8.29
- Conclusion: don't install phpunit/phpunit 4.8.28
- Conclusion: don't install phpunit/phpunit 4.8.27
- Conclusion: don't install phpunit/phpunit 4.8.26
- Conclusion: don't install phpunit/phpunit 4.8.25
- Conclusion: don't install phpunit/phpunit 4.8.24
- Conclusion: don't install phpunit/phpunit 4.8.23
- Conclusion: don't install phpunit/phpunit 4.8.22
- Conclusion: don't install phpunit/phpunit 4.8.21
- Conclusion: don't install phpunit/phpunit 4.8.20
- Conclusion: don't install phpunit/phpunit 4.8.19
- Conclusion: don't install phpunit/phpunit 4.8.18
- Conclusion: don't install phpunit/phpunit 4.8.17
- Conclusion: don't install phpunit/phpunit 4.8.16
- Conclusion: don't install phpunit/phpunit 4.8.15
- Conclusion: don't install phpunit/phpunit 4.8.14
- Conclusion: don't install phpunit/phpunit 4.8.13
- Conclusion: don't install phpunit/phpunit 4.8.12
- Conclusion: don't install phpunit/phpunit 4.8.11
- Conclusion: don't install phpunit/phpunit 4.8.10
- Conclusion: don't install phpunit/phpunit 4.8.9
- Conclusion: don't install phpunit/phpunit 4.8.8
- Conclusion: don't install phpunit/phpunit 4.8.7
- Conclusion: don't install phpunit/phpunit 4.8.6
- Conclusion: don't install phpunit/phpunit 4.8.5
- Conclusion: don't install phpunit/phpunit 4.8.4
- Conclusion: don't install phpunit/phpunit 4.8.3
- Conclusion: don't install phpunit/phpunit 4.8.2
- Conclusion: don't install phpunit/phpunit 4.8.1
- Conclusion: don't install phpunit/phpunit 4.8.0
- Conclusion: don't install phpunit/phpunit 4.7.7
- Conclusion: don't install phpunit/phpunit 4.7.6
- Conclusion: don't install phpunit/phpunit 4.7.5
- Conclusion: don't install phpunit/phpunit 4.7.4
- Conclusion: don't install phpunit/phpunit 4.7.3
- Conclusion: don't install phpunit/phpunit 4.7.2
- Conclusion: don't install phpunit/phpunit 4.7.1
- Conclusion: don't install phpunit/phpunit 4.7.0
- Conclusion: don't install phpunit/phpunit 4.6.10
- Conclusion: don't install phpunit/phpunit 4.6.9
- Conclusion: don't install phpunit/phpunit 4.6.8
- Conclusion: don't install phpunit/phpunit 4.6.7
- Conclusion: don't install phpunit/phpunit 4.6.6
- Conclusion: don't install phpunit/phpunit 4.6.5
- Conclusion: don't install phpunit/phpunit 4.6.4
- Conclusion: don't install phpunit/phpunit 4.6.3
- Conclusion: don't install phpunit/phpunit 4.6.2
- Conclusion: don't install phpunit/phpunit 4.6.1
- Conclusion: don't install sebastian/version 1.0.5
- Conclusion: don't install phpunit/phpunit 4.6.0
- Conclusion: don't install phpunit/phpunit 4.5.1
- Conclusion: don't install phpunit/phpunit 4.5.0
- Conclusion: don't install phpunit/phpunit 4.4.5
- Conclusion: don't install phpunit/phpunit 4.4.4
- Conclusion: don't install phpunit/phpunit 4.4.3
- Conclusion: don't install phpunit/phpunit 4.4.2
- Conclusion: don't install phpunit/phpunit 4.4.1
- Conclusion: don't install phpunit/phpunit 4.4.0
- Conclusion: don't install phpunit/phpunit 4.3.5
- Conclusion: don't install phpunit/phpunit 4.3.4
- Conclusion: don't install phpunit/phpunit 4.3.3
- Conclusion: don't install phpunit/phpunit 4.3.2
- Conclusion: don't install phpunit/phpunit 4.3.1
- Conclusion: don't install phpunit/phpunit 4.3.0
- Conclusion: don't install phpunit/phpunit 4.2.6
- Conclusion: don't install phpunit/phpunit 4.2.5
- Conclusion: don't install phpunit/phpunit 4.2.4
- Conclusion: don't install phpunit/phpunit 4.2.3
- Conclusion: don't install phpunit/phpunit 4.2.2
- Conclusion: don't install phpunit/phpunit 4.2.1
- Conclusion: don't install phpunit/phpunit 4.2.0
- Conclusion: don't install phpunit/phpunit 4.1.6
- Conclusion: don't install phpunit/phpunit 4.1.5
- Conclusion: don't install phpunit/phpunit 4.1.4
- Conclusion: don't install phpunit/phpunit 4.1.3
- Conclusion: don't install phpunit/phpunit 4.1.2
- Conclusion: don't install phpunit/phpunit 4.1.1
- Conclusion: don't install sebastian/version 1.0.4
- Installation request for phpunit/phpunit ~4.1 -> satisfiable by phpunit/phpunit[4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.4, 4.1.5, 4.1.6, 4.2.0, 4.2.1, 4.2.2, 4.2.3, 4.2.4, 4.2.5, 4.2.6, 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.5.0, 4.5.1, 4.6.0, 4.6.1, 4.6.10, 4.6.2, 4.6.3, 4.6.4, 4.6.5, 4.6.6, 4.6.7, 4.6.8, 4.6.9, 4.7.0, 4.7.1, 4.7.2, 4.7.3, 4.7.4, 4.7.5, 4.7.6, 4.7.7, 4.8.0, 4.8.1, 4.8.10, 4.8.11, 4.8.12, 4.8.13, 4.8.14, 4.8.15, 4.8.16, 4.8.17, 4.8.18, 4.8.19, 4.8.2, 4.8.20, 4.8.21, 4.8.22, 4.8.23, 4.8.24, 4.8.25, 4.8.26, 4.8.27, 4.8.28, 4.8.29, 4.8.3, 4.8.30, 4.8.31, 4.8.32, 4.8.33, 4.8.34, 4.8.35, 4.8.4, 4.8.5, 4.8.6, 4.8.7, 4.8.8, 4.8.9].
- Installation request for phing/phing dev-master -> satisfiable by phing/phing[dev-master].
- phpunit/phpunit 4.1.0 requires sebastian/version ~1.0 -> satisfiable by sebastian/version[1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.0.6].
- Can only install one of: sebastian/version[2.0.0, 1.0.0].
- Can only install one of: sebastian/version[2.0.0, 1.0.1].
- Can only install one of: sebastian/version[2.0.0, 1.0.2].
- Can only install one of: sebastian/version[2.0.0, 1.0.3].
- phing/phing dev-master requires sebastian/version ^2.0 -> satisfiable by sebastian/version[2.0.0, 2.0.1].
- Conclusion: don't install sebastian/version 2.0.1Installation failed, reverting ./composer.json to its original content.

Я уверен, что я установил curl и моя версия php 5.6. Пожалуйста, помогите мне.