Why does a VI work in a blank project, but not in a myRIO project?

I'm building a calculator in LabVIEW that connects to the myRIO. 

In a blank project, the VI works perfectly. All the operators function as required. However, when I copy and paste the block diagram into a new myRIO project, the VI no longer works. When I press a button instead of printing it on the string indicator, it is unresponsive.

So my first question is, why does a LabVIEW VI work in a blank project, but not in a myRIO project? Is it the event structure? Secondly, how can I adjust the VI so that it functions in a myRIO project?