Laravel 5.1 localization exception

My laravel localization works fine with one exception. Right now I have 2 locales, EN and CS. When EN is on, everything works, but when is active CS then there occurs an error:

Unable to choose a translation for "Před 5 měsícem|Před 5 měsíci" with locale "cs" for value "5". Double check that this translation has the correct plural options.

Interesting is when I comment out this translation in EN locale and run web with locale EN and fallback locale CS it works perfectly.

EN: :month month ago|:month months ago

CS: Před :month měsícem|Před :month měsíci

And here is how it's called: Lang::choice('site/post.time-hour', $interval->h, ['hour' => $interval->h]);

via Chebli Mohamed