In order for Stored Processes to execute from Web Report Studio, they must be stored in a special location in the metadata known as the "BIP Tree" folder.
Looking at the SAS Log might help, if you are getting a SAS Log. If you are not getting a SAS Log, but are getting Java error messages, then you might consult the Platform Administrator documentation for help. Otherwise, there are other possibilities that might be involved, but your best bet for a quick response to this issue is to contact Tech Support.
cynthia