I have had trouble before as well. My advise is to make sure you do the following. When you make your initial press on the lower center of the frame, hold the press down on the frame without letting it up. Then rotate the tab bender toward you as far as you can to extend the the tab to the straight up position. Then, while still holding the press down on the frame, rotate the tab bender around back to the original position and then continue rotating away from you as far as you can to bend the tab down onto the crimped area. Once you have executed those two rotations with the tab bender, raise the press off the call frame and continue to bend the tab away from you, further onto the frame. Then bring the tab bender back to its original position and use the press to crimp the tab more securely onto the center of the frame one last time. Any deviation from this sequence has given me issues in the past. If you get accustomed to this sequence you should be good to go. Also, make sure you've got the frame bracket properly adjusted so that the frame tab is aligned with the tab bender and the press. You can try testing this on a frame with no latex to ensure you're doing it correctly. Hope that helps.
