Problem with overclocking

I've got a problem with overclocking in AMD Overdrive. When I set the memory clock and apply it works. When I set the GPU clock and apply it won't work, sometimes it goes to the desired clock but jumps back after about 5 seconds. I've had success overclocking in the past. I don't know why it won't work now, is it a software or a hardware problem?
Hardware info:
Software info:

EDIT: I've also tried it with MSI Afterburner, won't work either.

why no use the catalyst software that comes with the card, thats what i use and is simple to use

When you put a load on the GPU do the clocks jump up to what you set? All GPU's these days drop their clocks in 2D mode (on the desktop).