There should only be a single instance of Tank Drive in that VI. You never want to define the same item twice with different variables The Tank Drive VI takes two numerical values, one for the right and left joysticks. I'm not sure what exactly you're trying to achieve with your current setup. I'm assuming you want to use the two Y-axises of the Xbox joystick as your controls. If so, I would use axis 1 for your left stick and axis 4 for your right stick. I do not have LabVIEW on this computer (we switched to Java), but your VI should look like this:
http://prntscr.com/9x2sk7