Here is what needs to happen. On your drivers halfshaft, on the innermost (towards tranny) end, there is a ring clip. play with it, get to know it. see how it moves around? thats why its a pita to put it in. now how i did it:
jack the car up, support it with jackstands. lay on your back under the car, and start to slide the shaft in. as you put in into the grooves, it should easily slide in an inch. then you get to the snap ring. gently move the inner cv casing in a circle and wiggle it to try to get that ring smooth all the way around the shaft. when you get it, the shaft will slide in another couple of inches, then click. you shouldnt be able to pull it back out now.
it is properly seated.
one thing to remember. The joints are like babies, never pull on them or they will come apart. thats no good.
hope this helped?