How come I can't tell the sex of my plants?

My last grow was Cindy99 and about a week into flower I could easily identify the males from females.

Now I am growing BC Kush x Mango Haze seed I got from Beanho. I am two weeks into flower and still have no idea which plants are male or female. They just are not showing. Is it the strain?

I am on a 12/12 light cycle and the room is totally dark and it does not get disturbed in the lights out period.

The only thing I can think of is that I transplanted on the same day I canged the light cycle. (I did not want to do it that way, but had too) So the growth may have been stunted while they got over the shock. They are growing now, but still not showing.

I have 5 plants in a small cabinet that is rather packed at the moment. I was hoping after I determined the sex to get rid of two or three males and then have plenty of room in the cabinet.

Any tips? Anyone familiar with this strain? Is there something else that may be wrong.

Thanks

just keep a close eye on them. only time will tell. best guess is your right about the transplant. everything else seems right