Blinds / Raising before the Flop

Hi,



Is the person who placed the bigblind allowed to raise when all other players only meet the big blind before the flop?



for example.



small blind is 10, Big Blind is 20



The bet goes around the table everybody puts the 20 in neccessary to meet the BB. (The person who placed the small blind puts the 10 difference to meet the blind.) At this point everybody has 20 on the table. - According to my understanding the betting is then finished and the flop must come...



A friend who had the BB recently tried to raise in this situation and caused an uproar. He thinks that the BB can raise in this situation!!!



who's right??

Your friend ist right. Of course you can raise, if u are the bigblind. Always!!