How Do I Fix My NEW Lawnmower?

We bought it about 6 months ago. I wanted to let the grass get tall for easter, but about knee length my husband couldnt take it anymore and cut it. Since then everytime he uses it, the grass WILL NO GO IN THE BAG! He has to rake everything when he's done. Pointless, thats why we got a bag kind. Its gas if that matters to anyone. Please email me the answer. Kaala79@yahoo.com