Oh, I just realized that perhaps your frame doesn't work the same way mine does. I only pin to the leaders... I pin the bottom of the backing on the lower leader, roll it a bit. I then pin the top of the backing & the top of the batting at the same time to the top leader. I then 'lock' my head and baste a line. Lay the top along that line and zigzag baste the top. Smooth it all out, clamp the sides & then baste the edges of the quilt top to the backing/batting.
Wish I could find the video I initially learnt this method from... it's been a LONG time
