PTR seems to be having stability issues which pushed back raid testing.
Future PTR questions or issues can be reported to the In Development subforum
For Retail PTR, Currently Midnight: #in-development:1205-public-test-realm
Classic: In Development > Mists of Pandaria Classic 5.5.4 PTR
PTR and Beta are run by the developers and QA, and do not fall under the normal Support group.
FYI, Mac tech support, while not able to answer this question, can be found at Support > Mac Technical Support