I’ve helped with this issue a couple of times now so thought it would be ideal to blog.
Basically when running a remote SQL instance, and adding in the Reporting Services Point, the Reporting Services server instance is empty.
To resolve the problem ensure that the Reporting Services site role is installed on the SQL server and not the SCCM server.
In Administration workspace choose Site Configuration>Servers and Site System Roles. Right click the SQL server and choose Add Site System Roles. Continue the wizard and add the Reporting Services Point.
So long as the SQL services reporting is installed and configured on the SQL box you should be good to go