I did exactly as u wrote and it worked just fine!!!
The problem is that this is an ugly hack that emulates what I need. Plus, admin has to check enrollments all the time, there is no way for moodle to signal a request. Studens also have no idea whats going on or when his request was approved couse no messages are sent to him.
In other words its an ugly hack. it works but... It would be nice to have this put in moodle definitly.
thanks for your help!!!