Thanks for clarifying, but the clarification doesn't help your position, which, it's become clear, is simply this: even though the Bush administration negotiated the troop pullout, it's the Obama's administration's fault that the agreement was followed.
It appears to me that the way you came to this position is because you believe that the Bush administration always intended for the agreement to be renegotiated and if the Obama administration had really wanted to leave US troops in Iraq, they could have.
Those beliefs are unsupportable.
When the Bush administration made the agreement, the US was in a position of power. If the Bush administration had wanted to keep open the open to leave US troops in Iraq, they could have made that part of the agreement. When the Obama administration tried to renegotiate the agreement, it was not in a position of power. The Iraqi government already had what they wanted.
Could the US have found something to concede to Iraq that would have kept US troops in Iraq? Probably. You cannot know what that would have taken, though, and so your blithe assertions that things could have simply been "negotiated away" illustrate nothing but your naïve understanding of the political situation.
You're trying to blame the Obama administration for not correcting an error made by the Bush administration. That position isn't logically supportable.