I would guess that it's timing issue. The ShellExecute() launches PDF printing and code execution continues before printing is completed. Your arbitrary 10 seconds delay may not be enough in all cases.

>Thanks Sergey. Here it is.
>

>
>LOCAL lcfile
>
>lcfile = m.pcfile
>
>if vartype(lcfile) <> "C" OR empty(ALLTRIM(lcfile)) 
>	messagebox("No parameters passed to printpdf.", 0+16+0,"Error")
>	return .f.
>endif
>
>**ShellExecute API declaration
>DECLARE INTEGER ShellExecute ;
>	IN SHELL32.DLL ;
>	INTEGER nWinHandle,;
>	STRING cOperation,;   
>	STRING cFileName,;
>	STRING cParameters,;
>	STRING cDirectory,;
>	INTEGER nShowWindow
>
>* Open.
>* ShellExecute(0, "Open", lcfile, "", "", 1)
>

>* Print.
>ShellExecute(0, "Print", lcfile, "", "", 0)
>
>return .t.
>
>
>