fvnfish, I have figured out the problem. Re-download Pattview. SAVE A BACKUP TO YOUR COMPUTER! Go ahead and do the converting process and import the pattern. After that, do not edit it with pattview. When you import the save file back to the Wii, the game will show that the pattern is black. Click on it and press edit, and your picture will be there and will allow you to name it. (you can do this in Able's if you want to keep it a pro design)
I haven't tried editing the pattern in Pattview, but you can try if you want.