DROPPED FRAMES WHEN GOING TO TAPE

I edit 720 59.94.  On occassion, I get a dropped frames warning when I go to tape (DVCPRO HD HD1400 deck).  I ususally do a video mix down and this solves the issue.  Other than that, are their any other settings I should look at to prevent dropped frames when going to tape (digital cut)?

Thanks!

Avid Media Composer 8.5.2

OS 10.9.5

Processor 3 GHz 8-Core Intel Xeon E5

Memory 64 GB 1866 MHz DDR3

Graphics: AMD FirePro D700 6144 MB

Mac Pro Late 2013

AJA IO4K