Open ZebraDesigner programmatically

Hi,

  I'm trying  to open an lbl file programmatically, because i want to print it with zebra designer, but I have an error:

"The program has encontered an error and needs to close. Any changes to the document since last save may have been lost."

i use this vb6 code:

WinWnd = ShellExecute(WinWnd, "Open", "C:\SampleEti.lbl", vbNullString, vbNullString, SW_SHOWNORMAL)

if I open the file by Run Command, it's OK.

What's wrong ??

Thank you

Manuele Ratti