Cant drag a sound clip right to left flush against a preceding clip

Question

I have a movie and I've added 2 songs.  The first song ends and the second song i dragged in is to the right of it, but about 8 seconds afterwards. 
I've tried dragging it left but I can't.
Why can't I drag it left to be flush with the preceding one?

Answer 1

To remove empty space at the end of a sound clip (region):
Drag the red playback line to where you want to make a chop.
Select the region you want to chop.
Either select "slice" from the edit menu, or press Command T. The region should now be divided into 2.
Click in the open workspace to deselect both parts.
Click the part on the right, the empty space part, to select just that one.
Press delete to delete it... and voila.. the empty space at the end of the region is gone.
There's a couple of things you can do if you want to be more precise in selecting the slice point. For example, you can slide the little zoom triangle on the lower left of the window to the right to zoom in.