Hi
I was curious myself as I think I will get something similar sooner or later.
Googling came up this
A few people have reported issues with the male SCT thread diameter on this item being a bit larger than necessary. We have tested our current batch and it works with Meade, Celestron, and Baader SCT accessories. However, it will not thread into William Optics accessories, and with GSO it is a hit or miss.
http://agenaastro.com/antares-f-6-3-...telescope.html
Could be the problem you are having.
Philip