Can't get it in!

Question:
	Hi. My boyfriend and I have been together for 6 months. We are both virgins and we have been wanting to have sex however we are unable to get his penis in. Some friends suggested that maybe I wasn't lubricated enough but after trying a lubricating substance we find that that is not the problem. We have tried various positions but find that nothing works. Please help as we both feel kinda stupid, how can we make this work and is this common?
Source