Samson Stage XPD2m Dual Presentation System

I bought the wireless microphones set and tried it out for a couple of hours during a rehearsal for a children theatre performance. The connection between transmitters and receiver was very unreliable, sometimes it worked ok for a little while, sometimes it would break and re-connect every other second, making it even more disturbing than disconnecting completely.
We rehearsed in a 150m2, I tried placing the receiver in different positions in the space (FOH and stage floor) and it didn't change much. They were never further than 20m away from each other.
I also got the impression that when the performers would look away from the receiver, and thus, their bodies would be in between transmitter and receiver, the connection would fall off immediately - sometimes re-connecting afterwards, but not always.
All in all, even if the sound was not bad (we only tried the headsets) the experience was pretty bad because it made the microphones unreliable.