Render error when attempting to render renamed psd file

Hi,

Has anyone had this problem? I'm trying to render a series of stills (photoshop psd files) at regular points along a timeline - all generated by a script. I can generate the renderitems just fine - I've attaced the script that does it.

When I try to render however, I get this error:

error: Can't copy from a file " / AEtemp-AADE9C- " that is empty (39 :: 0)

and are my filepath and new filename - but the AEtemp portion is generated by after effects. What results are files that are about 40K bytes but are not valid photoshop files.

When I don't try to rename the render output file, after effects generates it's own name with a file sequence number and this renders fine.

I hope I'm being clear. Any help would be appreciated



var frameSpeed = theComp.layer("control layer").property("Effects").property("speed").property("Slider").value;
var retPathObj = new Folder().selectDlg("Pick a folder");
for (var i = 0, startPos = 0; startPos < theComp.duration; i++, startPos += frameSpeed) {
var renderItem = app.project.renderQueue.items.add(theComp);
renderItem.timeSpanStart = startPos;
renderItem.timeSpanDuration = theComp.frameDuration;
renderItem.outputModules[1].applyTemplate("Photoshop");
renderItem.outputModules[1].file = new File(retPathObj.fullName + '/' + theComp.name + '_' + i.toString() + '.psd')
}