There are four main attributes to make sure are set correctly.
ATTR_HORIZONTAL_GRID_VISIBLE - Inside the control, not the cell
ATTR_HORIZONTAL_GRID_VISIBLE - Inside the cell, not the control
and the same but VERTICAL instead of HORIZONTAL.
Also be sure the color (another attribute) is set to something other than the background color. These options alone should be able to get the desired results, if this is still not working, please post some example code for what exactly you are changing.
Brandon Vasquez
Applications Engineer
National Instruments