Visitor Visa - B2

           I am a 21-year-old Egyptian student. I study civil engineering in Egypt. I applied in the U.S embassy in Cairo and the interview was today. And here is the dialogue between me and the VO

VO : good morning
Me: good morning

VO: where are you going the U.S
Me: Hawaii

VO: WOOOOW Hawaii but why Hawaii?
Me: because I want to visit Waikiki beach, manoa falls, honolulu zoo
and Hawaii has many excellent attractions which doesn't exist anywhere else

VO: again why Hawaii? (He was not convinced why hawaii especially)
Me: repeated the same reasons

VO: who is sponsoring you?
Me: my dad

VO: Will he travel with you?
Me: No

VO: What does he do?
Me: He is a civil engineer

then VO started typing for about 2 minutes then said .....Sorry I can't grant you the visa
and he gave me the 214(b) slip

and he didn't ask for any documents

I visited UK before for 2 months (I was a student there but I didn't continue my study there)

So what do u think the main reason for refuse???