Is it me or does it seem like alot of people do not get their private message
untill way late due to the fact that it's so small . I have PMed members on a few occasions while they are logged on and did not get a responce till the
next day or so, on the flip side I sometimes do not notice that I have a PM
because Im reading up on a post.

Suggestion.... Maybe do a pop up (you have a PM) just a thought.

 

People not answering PMs has no bearing on the size of the PM box. The fact that a member receives the PM (rather than getting the "box full" message) is evidence enough of that.

People need to check the box indicating that they want to be notified when a new PM arrives:

Members > Edit Options
Scroll down to the Messaging & Notification section to the Private Messaging frame.
Check the Show New Private Message Notification Pop-up check box.
Scroll down and click the Save Changes button.