Still trying to get my head round 2.5… Pre-2.5 in order to get an object (eg a wheel) to rotate along a path I added this driver to the ipo curve and all was well:

b.Ipo.Get(“ppspeed”).getCurve(“Speed”).evaluate(b.Get(“curframe”)) * (47.5/21.1) * (-36), where 47.5 is the length of the path and 21.1 is perimeter of the wheel. This approach originally came from this very forum:http://blenderartists.org/forum/showthread.php?t=72162and though I’m no programmer it’s simple enough for me to have used very successfully many times. Problem of course is that 2.5 doesn’t like it: “ERROR: Invalid Python Expression”.

Could someone tell me how to get this to work in 2.5, or an alternative approach which does the same thing?

Thanks in advance, Clive.