Here’s what I’m pretty sure is happening. When you first click, LVAR1 is equal to +. When you attempt to add 1 to that it concatenates them since + is a string that can’t be treated as a number. So the result is +1. When you click the second time, LVAR1 is equal to +1 which can be treated as a number, positive one. So instead of concatenating them Axure will treat both sides of the plus as numbers and add them. From here on out it works as expected.