I don't personally have one of the new Smoktech pyrex tanks, so I can't say from experience about the quality fit & finish of the parts and o-rings.
Since you have determined the leaking is not coming from the carto itself (leakage from the carto connector air hole), I suspect a problem with the inner o-rings. These are what make the seal between the caps and cartomizer to prevent leakage. Either they are defective, torn, or the wrong size.
Is this your first experience with a cartotank? If so, care needs to be taken when inserting a cartomizer into a tank. The inner o-rings are vulnerable to being damaged by the sharp top edge of the cartomizer during assembly.
There are tank tools available which not only make assembling and filling a tank easier, but also protect the o-rings from damage by covering the carto's opening during assembly and filling. My suggestion is to get a Slap Yo Moma tank tool from Big Daddy Vapor.

Slap Yo' Mama Adapter : Big Daddy Vapor
Meanwhile, you will likely need to find a replacement o-ring for your tank. Contact the vendor that you purchased your tank from for an o-ring replacement.