Prblem found

I just installed the GMap and Location modules and am in the process of configuring. It all seems to work except no map is displaying at all (in the location section of a new node and the GMap site configuration). I got an API key from google and inserted it. Does it take time before the key should work or will it work right away? I've experimented with the zoom and lat long default settings in the administer->Site Configuration->GMaps but all I get is a grey box. I've looked around at other postings here but not found a definitive answer. What am I missing?