There is at least 3 things that might be wrong.
First of all, you are loading from $2007, you do a ROR operation on it, and discard the result (you don't store it anywhere). How could this work in the 1st place ? You need to write something write to $2007 for the change to be effective !
Then, 2nd problem, ROL and ROR does a 9-bit rotation, with the carry bit. What ROR does it :
Cin -> word -> Cout
Which is probably not what you want. Instead you'd want to do :
[write something back to $2006]
3rd problem : Are you running this code during VBlank ? If you are, then fine, otherwise, it will never work as VRAM can't be accessed. (lda $2007 and sta $2007 will do Bad Things (TM). More seriously, this means doing so will have a completely unpredictable result, will mess the scrolling showing garbage on screen, etc, etc... ).