Label scale problem

[earache]

Keyshot noob here.  I'm having some issues with the scale of my labels and was hoping for some advice.

Let's say I have a 100mm square cube loaded into Keyshot and I want to place a 100mm square label onto one of the faces.  I save off a properly sized PNG from Illustrator, load the label and project it onto a face.  I would expect the label to come in at 1:1 scale and project onto the face exactly as I had designed it.  But it always comes in off center and out of scale by a little bit.  In this scenario it's a minor annoyance, but if I'm trying to place a label onto a keypad for example, it ends up taking a lot of time to get the position and scale just right.  Am I missing something here?  Isn't there a way to automatically scale and map the image onto a face?  Thanks for any help.