I am currently having a problem with my cruise control. If i push the button on the end of the cruise stalk the green "cruise" lights up on the dash but when i push the leaver up or down it doesnt lock in to set that speed.

Does anyone know or can point me in the right area, how to fix this problem?

My TE does that exact thing with the cruise control it's a bit of a mystery to me as well.

Check the hose going from the throttle body to the vacuum pump for security and cracks/leaks. If it looks alright, remove the vacuum pump and test it with 12V (if you need pinouts let me know). I had found my pipe had been mistakenly placed back onto the intake manifold rather than the cruise plunger so make sure that's all correct.

You can test the plunger for movement by sucking on the pipe with your mouth, you should be able to see the pin go up as you suck on the tube... sounds bad but it's really not :P

check the vacuum line to the throttle body and the stop light switch (4 wire, 2 circuits)

also check the four screws on the top of the throttle body. they provide the clamping force to seal the vacuum diaphragm. I lost one and my cruise started intermittantly acting up.