This card need fixing. Fusion summon this card to the field and then it can't activate its effect. and there is nothing stated in the description about it can't be activated due to a situation
Sometimes crusher + chargeman since they usually become hinderance and bricks in my deck, sometimes lv 4 + photon dragon. In some cases it worked, after many trial and error so far my hypothesis is you need to have no monster in hand
Do you have 2 empty Monster zones on your side of the field? You have to Special Summon both materials, so if you don't can't Special Summon both at the same time, you don't get to Special Summon anything.
If you always have 2 empty Monster zones, then maybe try saving a replay when that happens again, and post the link here so others can see it too. You might have missed something else.