Vault error: 200

I am getting an error when I check into PDM Workgroup.Message says:

Vault error: 200
Invalid revision syntax.

Failed on check in of document [document]
Check in aborted.

The part it's trying to check in is a standard library reference,should not be trying to check it in at all. But it is and poppingup this error. Any help is appreciated.

Thanks.SolidworksWorkgroup Pdm