Programms can not use current iTunes-Music

Hey you guys!

I really need help.

After installing Virtual DJ, I was wondering, why my new albums are not available in the music selection of the program. I can only browse through my "older" music, which not includes newer tracks and stuff.

Now, with my new Windows Phone, I installed "Windows Phone 7 Connector" and selected the button "Import all music data". On the right, there is a list, where I can see the different artists but also here, there are a few missing.
After synchronizing with my mobile phone, I noticed, that there are also newer tracks missing.

So my problem is, that my programs can only load "older" music, but not the current music which includes my last added albums.

I have already searched the web but have not found something.
I am very grateful for any help.

Regards

PS: Sry for my English, I'm a German student.