Ajax :: XMLHttpRequest Stuck At 0

It is day two of the same problem (and day two of learning Ajax, day five of Javascript)

The current code (below) does nothing; it does not go into the showContents function. Switching the order of some items would cause it to enter the function, but it would always alert that the xhr status was 0. I guess this is an improvement?

php doc that is getting requested (I don't think the error is here as the problem is that it is not even initializing):

Code:

javascript code that is requesting the information:

Code:

I need to pass the num variable because the fields I am dealing with are part of a bunch of fors that create an unspecified number of fields titled 1source, 2source, 3source, etc.