Its tribute summoned. maybe your lvl 7 monster is not tribute summoned it can be SPECIAL summoned (from grave,etc) you must perform normal tribute summoned a monster, not SPECIAL summoned it. hope it help
I had the same problem but I figured it out. It usually don't work with some effect monsters, that's because the card only negates the ACTIVATION of an Effect Monster Effect; but some effects are not activated they are inherent to the card. My example: BEWD tribute summoned attacking a Cat Ears Tribe; Overwhelm didn't trigger because Cat's effect is not activated and I was screwed
you need to set first your overwhelm and wait for your opponents turn before it can be activate, and make sure that you already switch your kazejin into face up attack pos. hopes this help
i tribute summoned bew with a kaiba man which the card still states is a tribure summon and overwhelm was on the feild for 2 turns and wouldnt activate when i was attacked with a monster whos effect was if it attacks a monster in defence to destroy that monster with no battle damage so the guy used enemy controller switched my bew to defence and destroyed it all while i was helpless to activate ov
Then, BEWD was summoned through Special Summon. Kaibaman effect: you tribute him (think like an Econ take or a Ritual Summon) to SPECIAL SUMMON a BEWD. That is different from a Tribute Summon