does anyone know why , whatever setting I have this on it makes my amp have a hissing radio-like noise when I play? I'm puting it into a Roland Cube amp with no distortion on.

Its really annoying. pretty loud but worse when the treble or presence on the amp is anywhere but zero! It isn't there just when the amp and effect is on, only when I pick n strum as well...

Thanks all!
someone else said in another post that cubes don't like having effects put into them.. Is this true? I would like to put some kinda sustain into my sound so I can get some smoother soloing cos Im not that great at it!
if anyone is interested I got a solution: plug all your amp and effects into one multi plug extension then put the plug extension into the wall. I'm not an electrician but you get lots of hum if they are into separate plug holes in your wall.