Photoshop CS4 gradient colour wont change from gray?

Okay well I am currently working on a background and have set up a template for it and it's all ready to edit but one problem, The colours don't work? it says "Layer1/Gray" and whenever I try to pull the gradient thing down it just does gradient in different shades of gray. I've been trying for hours to make it coloured but it just wont work! and Yes I have the gradient colour on!