Why am I having problems shifting into 3rd gear?

I own a 2001 Mitsubishi Eclipse Gt (5-spd). Casual driving it is great, but when really pushing it 1st and 2nd gear go by like a dream but when I go to quick shift into 3rd its like hitting a brick wall and wont go into gear and it stays in neutral so I have to granny shift it into 3rd. Any reasons why? Is this common with 3gs? I think it might be that it seems like I shift straight up when I go from 2nd to 3rd although Ive never put it back into 1st gear, I think it might be that I don't shift going into a small angle? but I'm not sure. Any input would be appreciated. Thanks