Help, Please! Last 3 quilt backs have puckered.
I have an Avante set up on a 10 foot studio frame. I finished my husband's 93x120 quilt in Feb 2011 and the top and backing were perfect. I'm using the same batting, good quality fabrics..batiks, stonehenge, and this last quilt had Jason Yenter and Marcus fabric. My husband's fabris were the Shadow Play line. These last 3 quilts have puckered on the back creating pleats in the crosswise direction on the back. No pleats lengthwise. On the frame the quilt sandwich appears to be smooth and with enough tension. I can't figure out what the problem is so I can correct it. Any suggestions?