It is generally considered inappropriate to use exclamation marks in narration, because it comes across as hyperbole. Save ’em for dialogue or for first-person narration (which is much like internal dialogue anyway).
There is no clear logical/cause-and-effect connection between ‘you can’t draw’ and ‘a bank is being robbed.’ To fix this, the sentence/paragraph needs a transition, some way to show why the bank robbery is relevant to both the ‘amazing power!’ and the problem.
You have the amazing power to make anything you draw become real. The only problem is that you’re terrible at drawing, and you don’t have time to become better, because right now a bank is being robbed, and you have to stop the robbers.