Wrist Pushups and Wall Extensions

Wrist pushups - so I cannot do wrist pushups except on my knees and that takes nearly all the weight off so I don't feel like I'm working at all yet I cannot do them if I put any weight on whatsoever. My wrists are extremely weak. Of specific note is that the left wrist pops and cracks and hurts through the transition from the top to bottom. What should I do?

Wall extensions - I understand that during the wall extensions you are supposed to keep your whole back against the wall and forearms touching. At the bottom my left forearm will absolutely not touch the wall and at the top neither arms will touch the wall. I cannot keep my lower back on the wall at all. Do I just keep going with it until my arms and back start to touch or am I doing it so poorly I am making things worse?

regarding your wrists:

Coach Sommer said:

Initially most people will find full wrist pushups too difficult to perform. I highly recommend that beginners to this movement begin from their knees. If this fails to sufficiently scale back the movement, then add additional piking in the hips until you reach a comfortable level of intensity during the wrist pushups.

Quote from:http://gymnasticbodies.com/forum/viewtopic.php?t=860&start=17#p4430

If wrist push-ups are still too demanding, substitute regular wrist stretching and include separate wrist workouts.

The classics like fist push-ups, (reverse) wrist curls (and twists) with light weights (maybe even a water bottle), wrist isometrics, towel pull-ups, fingertip push-ups, wringing out the towel, wrist push-ups against a wall and rice bucket come to mind... . The list goes on and on.

Try doing the wall extensions on the ground, on your back. When those are smooth and the forearms are flat all the way through try again on the wall.

Or do the ROM that you can do and slowly increase that

Just switch it around. Do your wrist pushups against the wall and do your wall extensions while on the floor.

Perhaps you could do the wrist pushups on an elevated surface, and progressively decline?