Data Conversion Error Message

I am getting the following error when running a report in Crystal Reports 2008:

'Database Connection Error: '42000:[Microsoft][ODBC SQL Server Driver][SQL Server]Error converting data type varchar to datetime. [Database Vendor Code: 8114 ]'

I can run my stored procedure without error in SQL Server. When I add the stored procedure to a new, simple Crystal Report, it runs without error and data is returned. The Crystal Report that is getting the error has been converted from Crystal Reports 8 to Crystal Reports 2008. There has to be something in the way the report is passing data to the stored procedure that is causing the issue. Any ideas?