So, in applying for graduate school, I asked a professor, whom I have been doing research with for a long time, to write me a letter of recommendation. He gladly agreed and promptly filled out all of the invitations except for the one at my current university. In reminding him through e-mail, I got no response from him and left it at that because it seems as though he knows what he's doing. However, to this day, he still hasn't submitted it and I am scared it will hurt my chances. I don't want to keep badgering him but at the same time, I want to know what is going on. what should I do?