Cossacs joining armies, a question.

[coturnix]

Playing with Siberian whites and have noticed that 3rd Ural cossacs division (with a 2 star leader) cannot join the Orenburg Army as corps. Guess this is a cossac trait and those divisions (like Dutov´s Orenburg cossacs) will never join an army? Can´t find anything about this in the manual.

[Orel]

I seemed to have a frequent problem like that when playing against the computer, and not necessarily with Cossack troops. It was quite often and always with one random division.