Why does 'cvs admin -l<branchname>' complain that my branch is ab sent?

[Whitlock, Ginger]

Hello CVS-Guru's

We're running Solaris 8, with CVS 1.11

Might someone help me with an error I'm receiving with attempting to lock a
branch in CVS?

I receive an error complaining that my branch is absent:

cvs admin:
/opt/cvs/customer1/software/src/com/gers/sales/order/persist/OrderDaoFactory
.java,v: branch customer1-0_5C1_00E absent  

running cvs log to verify the branch exists :

   customer1-0_5C1_00E: 1.11.0.2   

and it does.

I thought I'd found a work around , (cvs admin -bcustomer1-0_5C1_00E
<repository>, to set the default to this branch then
cvs admin -l -L <repository> , to lock what is now the branch at 'tip' ,
followed by cvs admin -b <repository> to set it back to the trunk)
....and this works well as long as every-single file on the branch has
actually been modified, if there are any that have not, the cvs command to
lock bombs with an assertion failed error from hash.c

I appreciate any assistance with this matter.

Thank you
Ginger Whitlock