Help! I lay down a floor of ceramic tiles on concrete with premix tile adhesive nearly two weeks ago now and only a select few number of the tiles have stuck, the ones that haven't stuck still have wet adhesive underneath them. The room is about 6m2, has no windows or heating. However it is in internal room and the surrounding rooms are heated. I don't know what to do!

Thanks

Will

Cold (outside, under slab, under 60), dampness in concrete, and large tiles (over 6 x 6)will greatly extend curing time.
If you are in a winter where you are, it's not a good time to put tile on a slab.
Dampness may mean it won't hold period.

And thin set would have been much preferred to premix adhesive.

Yeah so the bad news is that most likely this adhesive was for wall tile. As previously mentioned floor tiles need to be set with latex modified mortar called "thinset" in the trade. Premixed adhesives do not work regardless of what they say for floor tiles. Thinset comes in 50 lb bags and must be mixed with water. Water based adhesives that are premixed often never dry behind wall tile either and create many long term problems. To be honest I am not sure why they are still used or sold. The good news is that you can remove the tiles you set easily without breaking them, clean them and reset them with the proper setting material.