Placing a displacement map in Maya 2010

[sfrenc21]

I am trying to place a displacement map on geometry that I have modeled with a rock texture but after placing the displacement map file into the displacement map Shader node, when I render my scene it doesn't show. I wanted to know what necessary adjustments I need to make in order for it to work. Do I need to make a better displacement map file, adjust the alpha gain or offset, or adjust the render settings?

[aabrams]

Can you post more like your displacement map and maybe a snap shot of your shading network?