Please post this question in DPM newsgroup
http://www.microsoft.com/communities/newsgroups/en-us/default.aspx?dg=microsoft.public.dataprotectionmanager
You can try the following solution:
In the Protection task area, click Modify Protection Group to update the configuration information for the data source on the DPM server and to increase the replica volume size if necessary. If modifying the protection group does not start a consistency check, run a synchronization with consistency check.
http://technet.microsoft.com/en-us/library/bb795681.aspx
Santhosh Sivarajan | MCTS, MCSE (W2K3/W2K/NT4), MCSA (W2K3/W2K/MSG), CCNA, Network+ Houston, TX http://blogs.sivarajan.com/ http://publications.sivarajan.com/ This posting is provided "AS IS" with no warranties, and confers no rights.
