Color identity and activated abilities

{"ops":[{"insert":"I think I understand the rules about color identity and the restrictions that puts on your 99, but Archdekt is flagging a couple of cards in my deck. I have a Brudiclad, Telchor Engineer deck, so of course I'm heavy with artifacts. Two of them are Cranial Plating and Skeleton Shard, both from the original Mirrodin sets, and both of which have alternate cost options for their activated abilities. Skeleton Shard is \"3 , Tap or B, Tap:....\" The card is an artifact, so it is itself colorless, and it has a colorless option for paying the activation cost, I certainly wouldn't think I could ever use Black mana to activate it's ability, but is it just a glitch that the deck builder is flagging it as a color identity issue?\nCranial plating is slightly different, in that it has a colorless equip cost and an alternative cost of \"BB: Attach Cranial Plating to a creature you control.\" This seems a little less clear since the \"Attach...\" ability isn't the same as the \"Equip\" ability. I would never expect to use the \"Attach\" ability, but maybe just having that text on the card means it can't be used at all. That seems pretty restrictive, and since losing that ability significantly nerfs the card I'm not sure it makes sense, but is it technically a problem to include a card that has an activated ability you CAN'T use? Or should it be treated (as I was originally thinking) as if the ability using the mana outside your Color Identity doesn't exist on that card in that deck? we're allowed to play a card with a hybrid mana cost if only one of the colors is part of our Color Identity aren't we?\n"}]}