If the VpeSetDevice is omitted everything works using the default HP driver set to A4. I can also print an identical label from Word to the Easycoder C4.
With the EasyCoder driver selected by VpeSetDevice:
VpeSetDevCopies causes a Kernel32 error
VpePrintDoc causes a Kernel32 error after the progress bar is briefly visible.
With these two commands commented out, the preview is good.