You'll either need to initialize the shift register by connecting a U16 constant to the left register outside the loop, or place a U16 Convert function from the Numeric>Conversion palette after the Increment function.
The default numeric data type is Double, so unless you specify what you want, that is what the Increment function will produce.
Ed

Ed Dickens - Certified LabVIEW Architect
Lockheed Martin Space
Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.