I'm trying to program the 16f610 using PBP2.60a and meprog/U2

The first word (0000) should be EF49 but it's failing to verify.
When i read it back it comes back with 2F49 3FFF 3FFF... etc

I have 12 of these chips, and it does it on all 12...

Other than all 12 chips being bad, what if anything could cause this problem?

Thanks