tab leaders in tables

Hi,

Anyone please suggest my code errors?

I need the leader dots in every first column of all the tables. tabs need to be stop before 6pts of the column width.

var myDoc = app.activeDocument;   

var myTable = myDoc.stories.everyItem().tables.everyItem().getElements();   

for(t=0; t<myTable.length; t++)   

{  

    var col = myTable[t].columns[0].select();

    var myFirstColumn = myTables[t].columns[0].width; 

    app.findGrepPreferences = app.changeGrepPreferences = null; 

    app.findGrepPreferences.findWhat = "(.+)$"; 

    found = app.selection[0].findGrep (true); 

for (i = 0; i < found.length; i++) 

{

  found[i].insertionPoints[-1].contents = "\t";

  TabStops.position = myFirstColumn - "6pt";      

} 

}

The code shows the below error.

Regards,

Velu