not able to add file to branch

[Vini]

hi all,
we are using WinCvs 1.3.12.1 beta (build 1).
i have a branch called "Version2-0-1" which provides symultaneous
development on Version 2.0.1 of the product.
we are able to make changes in files of branch and to store them and
it provides all functionality, suppossed for a branch.

the problem is, when we try to add a new file in this branch, it says
the file can not be added to sticky tag. we checkout the module with
the same name as of the branch and then we are able to store the
changes but not to add files.

the error message is 

cvs add ACDrawGraph.cs (in directory N:\AppSeekerClient)
cvs server: cannot add file on non-branch tag Version2-0-1

any ideas...

TIA
"Vini"