Record limit with JDBC connection??

I have a Crystal 2008 Ver 12.3.0.601 report that runs successfully using a regular ODBC connection. There are approximately 124,000 rows returned. When I switch the connection to a JDBC and try to run, either Crystal crashes or I get a "Failed to retrieve data" message. I'm 99% certain is has to do with the number of rows, but I don't know what to modify to allow it to return more. I've changed the JVMMaxHeap (to 96000000) and CacheRowSetSize (to 100000) in my CRConfig.xml file, but I'm still getting the same results. Any help would be greatly appreciated - thanks!