Why can't i add song after enabling itunes match ?

Hi , so i've bought itunes match last week , since then it seems i can't add any new song from my computer to iTunes.. each time i drag and drop or add song from the iTunes menu nothing happen. The # of items stays the same :/.. Any one has an idea why i can't add any new song since iTunes match is on?

My current system infos : Win 64bits , i7 860 OC 3.33ghz , 12Gb DDR3 Ram , Crucial M4 SSD , Geforce 560 Ti.

If you guys need any other info let me know in the thread.

Thanks in avance!!!