[Dx4win] Group number problem

[Allan H Pettersson]

I am using DX4Win 8.05.
I have created a group number for every contest and I have created group numbers up to 262 without any problems.
Then I did a  F8 search for every contest, did a "Multiple QSO Operations/ Set Group number" and it did work fine up to group number 253. 
When I try to do "Multiple QSO Operations/Set Group number" with group number 254 I get a small window saying "Error Value is not within required range"! But I can still put in group number 254 (and so on...) in the QSO entry window, QSO one by one! 
Is there a limit att group number above 253 or is the "Multiple QSO Operations/Set Group number" not prepared for operations from 254 and up?

Allan / SM5CSS - 7S5S