So a quick definition is:
Loaded - Tag was Loaded successfully
OK - Tag fired successfully (send method was called and completed.)
If you are seeing Loaded, but not OK. Then 1 of 2 things are happening.
1) The send function isn't being called, this can happen if under the Advanced settings the Send Flag is turned off
2) There is an error in the tag template or extension, that is stopping it from firing.
Your best bet would be to look in the developer console in your browser, and see if there are any errors.
You can enbale utag debugging by setting the cookie: