Thanks Dave.  I have one of those charts from a magazine and refer to it often - I'll have to do a comparison between the two. Much better than me guessing on pilot hole size.

The wood isn't raising, but instead there is a gap that "appears" between the box and the base.  The screws aren't drawing them together but rather seem to push apart. I think I'm using the right type of screws.  Will take a look again tomorrow.