CRYSTAL Report 2008 SP4 Ref to CR XI R2 Developer 2006

Hi Team

We are currently using CRYSTAL Report 2008 SP4 to develop report in our application and make a reference of crystal reports dll. Now we are going to use the CR XI R2 Developer 2006. My question is if we use CR XI R2 in our application to compile and build the app, and the deployment machine [UAT\PROD] is having CRYSTAL Report 2008 SP4, what could be the possible bug thrown by the system?.