It is almost right! If the meaning of your sentence is to tell a person that you cannot remember his/her name, then it should be, "Your name just isn't coming to me." "Does not" is continuous. It implies that the condition will not change. In this case, using "does not" implies that you will continue to not remember his name. If you use "is not" or "isn't," it implies that the condition is temporary. She doesn't go to the park after dark. This means that she always avoids the park at night. She isn't going to the park after dark. This means that, in this instance, she is not going to the park. Notice that it also changes the conjugation of the verb. I hope this helps.