Why do I have trouble talking to girls in person?

I think the reason is because of the lack of communication I have with them. I'm 19 years old, in College, never had a girlfriend, or dated one. I never even hung out with one. I'm a very nice person, and my friends always tell me how I'm one of a kind and an amazing person. I noticed that when I talk to girls in person, I may have a hard time keeping their interest, but when I talk to them on Facebook or MSN, I am able to make them laugh a lot....and I mean A LOT! I know that they don't laugh like this with everyone because I've asked them ';do you usually laugh this much, or is it just with me?'; Most of them say it's just with me (I'm gifted maybe? And yet no girlfriend lol). I find that when I chat with girls online, I have a bit more time to think of what I should say, but in person, sometimes I find it hard to keep going with the conversation because I go blank. Is there something I can do to help me keep up with these face to face conversations, or is it just practice?Why do I have trouble talking to girls in person?
yes , it's need more practice and practice ,

now , now I'am 25 year old , I can't imagine to talk with girl for one day ever , but

now I can talk to any girl easely , before I was think that when you talk with girl , talk in love , now I think it's no , first when you talk with girl , firstly for example if you walking in streat , and you see a girl , and you want to talk with her , ask her about the road about the streat and tell her after what your name ? , or where you from ? like that , and after tell her , try to talk with her more and more free as you talk with your boyfriend , talk with her about her country , her hoppy , and also you must guess innocent girl from her eyes , her face , don't be shy , and little by little by practice you will know how to talk with girl .Why do I have trouble talking to girls in person?
Thats exactly how I am but with boys, I think it requires more practice I kind of am the type to keep to my self so I think maybe talking to random objects pretending like there a girl will help.