Extendscript in Premiere Pro - change picture

Hello,

I have imported MOGRT into Premiere Pro.

Using Extendscript I am able to change the text in that MOGRT but not the picture.

Why is that?

I am using this method:

app.project.activeSequence.videoTracks[1].clips[1].components[2].properties[3].setValue("m:\\a.png",1)
all indexes are correct and this command returns true, however not changing anything.

Maybe the path is incorrectly written?

Can someone help me?