I was shooting today and noticed I was shooting a little low at 20 yards so I moved the pin down so I would shoot good again...well it worked for about 5 shots and then it shot low again and I reajusted it again... shooting good. get my arrows go back and shoot again and now I can't go down any more with my 20 yard pin so I put the 30 yard pin on it and shot good but guess what happend after 5 or6 shots? it did it again... so here is a picture I hope you know what is wrong here! the arrow was perfectly levela week ago.