Ditra mat / decoupling mat and tanking a bathroom

[u587162]

I've used Aqua seal to tank a wet room area on the walls and the floors.

I have Ditra mat bought for the whole house flooring. Should I also be using the Ditra mat / decoupling mat on the floor which has also been aqua sealed? Our floor has wet underfloor heating with levelling compound on top.

I guess that ditra mat helps stop tiles cracking if any movement in the floor but I understand it also acts as a water seal too?

Thanks.