In pp_fxaa3.c you can also try to comment out line 45 to 47 to see if you still don´t see anything then. If you don´t, open pp_fxaa3_luma.fx and set the shadermodel to 2.0 and see if you see something then.
+
Try to uncomment (remove the comment tags in front of it) the
#define SDSF_IGNORE_COMPILED
So even after this it was black? o.O
Did you ever successfully use any postprocessing effect? -.-