Need help: Unable Flatten pages because of Security setting

this is my code in myFunctions.js

var myFunctions = app.trustedFunction(function()

{

        app.beginPriv() ;

        this.flattenPages() ;

        app.endPriv() ;

    })

and this code in vb

app.myFunctions()

but I am getting exception as Security settings are failng to flatten pages.

any idea?