you need to set the database source at run time.
Dim cRep As New CrystalReport1
Dim crConInfo As New ConnectionInfo
Dim crLogInfo As New TableLogOnInfo
With crConInfo
.ServerName = "ServerName"
.Database = "Database"
.UserID = "UID"
.Password = "PWD"
End With
crLogInfo.ConnectionInfo = crConInfo
cRep.Database.Tables(0).ApplyLogOnInfo(crLogInfo)
Don't forget to use ApplyLogoninfo it will change the login details of the objects used in the report and then only report will work with the new database.
HTH.