Feature pack and R2 clients In AX 2012

If you are facing problem while use both AX 2012 Feature pack and AX 2012 R2 clients at a time in your machine. Feature pack clients not supporting R2 client and vice verse then you try following.

Yes Its right , there is no Microsoft Dynamics AX 2012 RTM component (AOS, client, Help Server, and so on) can co- exist with Microsoft Dynamics AX 2012 R2. Therefore, you must upgrade all components because there is no backward compatibility across components.

http://www.microsoft.com/en-us/download/details.aspx?id=28701