The storage control module occupies the entire screen, so it needs to be the only module installed for it to do anything. This is entirely non-obvious, though. If you put a storage control module and another module in the same screen, it should indicate why it's not working instead of just not doing anything.

(EDIT: Some other modules are like this too. In general, when a module needs more screen real estate than it can have, it should say that instead of just being blank.)

EDIT 2: Good place to check: https://github.com/McJty/RFTools/blob/25ee85b813badcf737362823ccf1528faa1b9252/src/main/java/mcjty/rftools/blocks/screens/ScreenTileEntity.java#L314