It looks like you have just about everything correct. The last answer was a good point, pointing out your format string syntax. If you are not familiar with how to format strings, you should take a look at this topic in under LabVIEW Help > VI, Function, and How-To Help.
I was able to get your application to work by changing the digits of precision on the front panel array. Try increasing that number and you should have your expected results.
