I can't seem to find anything at all about this model. Did you buy it new from a store or used from a classified?
If it's new from a store I'd be inclined to return it.
Does it sew OK just straight stitching and reverse? Try re-threading it and put a new needle in. Also make sure it's the right needle for the machine.

I still don't know why, but it seemed to be a threading issue.
Although i did it actually the same way as before.

I just get really nervous when i buy expensive things and they don't work as you expect ;)

Thanks for your reply