If you are just trying to have it reset to zero each time you rerun it, just wire a zero to the left terminal of the shift register. What you have is refered to as an uninitialized shift register, which we use a lot as a storage element, allowing a vi to remember its last values from one run to the next (while still in memory). You will see references to "LabVIEW 2 style globals" or "Functional Global Variables" (FGV), which are vi's that take advantage of this feature. Of course, in your case you don't want to!
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