"Miscalling", I define it as follows:
A player who says he has a hand (I will describe as X), when in fact his hand is something different, usually NOT a winning hand.
For example, Player A says I have an Ace high flush, when you look at his hand clearly, he does not have an Ace high flush as he thought the Four (aka 'the one legged Ace') was an Ace. Along the same line, a player says he has a flush, but one of his hole cards is in fact the other suit of the same color.
I can accept mistakes such as the above from new, inexperienced players, I cannot accept such mistakes from a known experienced player (although I am sure we have all made similar errors from time to time). Did the player deliberately miscall his/her hand in an attempt to get the other player to muck? If so, it is a violation of the rule.
The important part is was the miscall deliberate or was it a genuine mistake.
Hope this helps!!