export frame from premiere pro

Hey,

I'm trying to export a frame from a sequence, based on a code i found in the examples,

app.enableQE();

var activeSequence= qe.project.getActiveSequence(); // note: make sure a sequence is active in PPro UI

if (activeSequence) {

var time= activeSequence.CTI.timecode; // CTI = Current Time Indicator.

var outputPath= new File("~/Desktop");

var outputFileName= outputPath.fsName + $._PPP_.getSep() + time + '_' + activeSequence.name;

activeSequence.exportFramePNG(time, outputFileName);

} else {

alert("No active sequence.");

}

And it doesn't do anything. It doesn't throw any errors either, i played around a bit and it's clear that the function exportFramePNG exists, and that the parameters are ok, but nothing happens.

when I do

$.writeln(activeSequence.exportFramePNG(time, outputFileName));

it returns false.

What's wrong, what can I do?

Thanks