Crop pdf in switch flow with Acrobat X Pro

[major]

Hi,
I created a simple switch 13 flow:
input folder - Acrobat - Output folder

Acrobat Flow Item parameters:
Open - Automatic
Command - Use Script with path to .js file

This is the contens of this file:

for(var i=0 ; i<this.numPages; i+=1)
{
this.setPageBoxes({ cBox: "Crop", nStart: i, nEnd: i, rBox: this.getPageBox("Trim", i)});
}

This works in Acrobat console window, but not in switch flow. Where i'm making a mistake? I forgot something?

Thanks for any help in advance!
M

[major]

--Solved--
According to doc, instead of "this" must be "$doc" in script!