because you are not rubbing it for her. some guys will reach down and keep her motor going. also sometimes maybe a little grinding against it may help. unless she does not like that. try grinding motion with a little bit of circular motion. (kind of like if you were mixing a bowl) also maybe before you may want to really get her much closer so she is more ready before hand. massage that g-spot for a little while. if you are not sure. its not the clitoris which some mistaken that being the g-spot. if you insert your finger in there and move it as if you were motioning for someone to come over to you. you can feel a slightly rougher patch towards the front. that area my man will have her climbing the walls and very much so ready for you to do almost anything. while you down there feel free to keep her clitoris entertained too.