Accepting the consequent but denying the antecedent?

If P then Q

Q therefore not P

asserting Q as proof of not P is at least a Non Sequitur , but I think it's further down the scale: Exclusive Premises error

"Non-sequitur"  is to me closer to irrelevant so that two premises may each be true, but one does not imply the other.

Consider this reframing

If P then Q

If Q then not P

Q therefore not P

When one if/then statement not only doesn't follow from the other, but actually contradicts it (regardless of order) their use in constructing a syllogism is unwarranted.  Here, the reframing reveals Circular Reasoning and Cherry Picking when one statement alone is relied on

One of the "if/then" assertions must be wrong, factually incorrect.

Hi, Rationalissimo! 

I’m not sure this argument form is even deceptive. It’s not even trying. But yes, a non sequitur, at least.

Though, I am not clear how you came up with “factual incorrect.” The argument doesn’t say anything about the world; it contains only variables. Unless I missed something 

Thank you, Rationalissimo

From, Kaiden 

I'm going to think of it this way. 

If  it barks , then  it's a dog .

It's a dog , therefore  it does not bark .

This is clearly a fallacy, and a pretty obvious one, but I can't name it.

Good Luck!