Without a copy of the Automator Workflow/Application/Service (however you have it configured) to analyze it's hard to say what the cause of the issue is! So if you like to attach a zipped copy of it to a reply I'll take a shot at debugging it.
Note: Use the "Use advanced editor" link in the upper right corner of the normal reply window to bring up the Advanced Editor where you'll be able to attach files via the Choose File button or Browse button (depending on the Browser) above the Post Message button!