Can't use the Burn Tool

[ham__smith]

I am trying to create the effect of shading on the type in this piece but cannot seem to get the burn tool to work on the type. I have the type and the image on separate layers and have tried editing the type as a smart object and have still not been able to use the burn tool. However, tools like the blur and smudge tool do work on the type. I am quite new to Photoshop and could definitely use a second pair of eyes on this one. 

[JJMack]

To use a separate layer I believe you need that layer to be 50% Gray blended in overlay  mode. Punch her in the eye....