I am trying to maintain some code that I did not write. Stepping through the code I found that it is the following line that is causing the problem.
ShellExecute(0, "Printto", "C:\USERS\me\TEMP\2\exportpdf.pdf", "ImagingPrinter", 0, 0)
It is returning a value > 32, indicating success.
That command is executed twice (not back to back: there is intervening code) with the exact same syntax both times.
1) The first call takes the C:\USERS\me\TEMP\2\exportpdf.pdf file (which contains the body of a report) and "prints it" to the output folder as \\SOMESERVER\OutputFolder\FullReport.pdf.
2) The second call is, best I can tell, supposed to take the contents of the updated C:\USERS\me\TEMP\2\exportpdf.pdf file (which now contains just a last page of a report) and append them to the end of the preexisting FullReport.pdf file in the output directory.
Concerning the second call, though, before ShellExecute() executes there is a PDF file named FullReport.pdf in the output folder: it contains the body of the report. However, after that one line of code (ShellExecute()) finishes executing, there is no longer a file by that name, but there is a file named Item2.grp. The lack of a file named Item2.pdf is an error and a messagebox informs the user of failure.
EDITED TO ADD:
I found that the ShellExecute(..., "PrintTo", ...) call causes Windows to search the Registry for a "PrintTo" shell command for Adobe. That command is:
“C:\Program Files (x86)\Adobe\Reader 9.0\Reader\AcroRd32.exe” /t “%1” “%2” “%3” “%4”
Where "%1" is the file name and "%2" is the printer name (and /t indicates "silent print": no visible Adobe window and no user intervention)
Therefore, the overall Adobe call -- ShellExecute(..., "PrintTo", ...) -- translates into the following pseudocode:
C:\Program Files (x86)\Adobe\Reader 9.0\Reader\AcroRd32.exe
“FileToPrint = C:\USERS\me\TEMP\2\exportpdf.pdf”
“OutputDirectory = \\SOMESERVER\OutputFolder; OutputFileName = FullReport.PDF”
Hope that helps.
Although I can see now how that line creates the output file, I still do not know why the existing .PDF disappears and a .GRP file appears.