When I try to reverse like on a slight angle road or a driveway (thats why I cant reverse park) the car wont move and it just revs as if its on handbrake or braking, but try it on level ground and its reversing fine. Checked the diff oil and tranny fluid and they are fine.

Any ideas?

Hmm, sounds odd....

Could be the bands are slipping just enough that the extra added resistence is causing it to do this.

What color is the fluid? If it's anything other than the original reddish color, you've got an internal problem that is causing the trouble. Any color other than red, or with a burned smell to the fluid indicates slippage of the bands.

Only other thing I can think of is that the linkage is out of adjustment, and the slight twist while the car is on an incline could possibly be just enough that it is not completely engaging the trans into gear.

colour is fine redish

might take it to transmission place

thanks