100% Polyester shirt from Baw Athletic

[cougarboats]

Hi. Im looking for help with some shirts. They are a Polyester jersey type shirt, from Baw. Stated on the shirts, I need to use a 65/9 ball needle. I have breaks about every 20-30 stitches, so I changed back to my 75/11 needle to see if I had the same problem...still several breaks and it just doesnt look clean. I have run several practices on this logo, and never had a problem, and it looked great..but it was on different fabric.
Is there anyone who has any suggestions? Please?!
Thanks, Danielle