composer install error

[samuelexyz]

[Composer\DependencyResolver\SolverProblemsException]
Problem 1
- The requested package cebe/markdown ~1.1.1 exists as cebe/markdown[1.
2.x-dev, dev-master] but these are rejected by your constraint.
Problem 2
- Installation request for yii2mod/yii2-cms * -> satisfiable by yii2mod
/yii2-cms[dev-master].
- yii2mod/yii2-cms dev-master requires cebe/markdown ~1.1.1 -> no match
ing package found.
Potential causes:

• A typo in the package name
• The package is not available in a stable-enough version according to you
  r minimum-stability setting
  see https://getcomposer.org/doc/04-schema.md#minimum-stability for mor
  e details.
  Read https://getcomposer.org/doc/articles/troubleshooting.md for further
  common problems.