Crystal Report Logon Failed Problem

I develop the Windows Form Application using C#. So, I'm using crystal report for bill printout. Using ODBC (RDO) connection create and set it is Crystal Report. But Comes "database login failed" error. It does not come "Windows authentication" user. It always comes to another user accounts. Sometimes, that problem solves at once but then comes always the same bill printout (Ex: invoice No 00020 always print its details). Plzz help