Set value of lookupfield from a url Get variable

Set value of lookupfield from a url Get variable

I have a form 'project_form1' that has a unique product_number1.  on save it opens a second form 'project_form2_stateless' with 

openUrl("#Form:project_form2_stateless?project_number2=" + input.project_number1, "same window");

I try now to assign the value in variable project_number2 to a lookup field 'project_number2' connected to project_form1, but is is not working , if I send the variable to a number field it works find?

How do I select a certain value in a lookupfield with deluge script on form load.

In other words I have a Lookupfield with the values 

17001
17002
17003

and i want the value 17002 selected on formload. 

Thanks for your advice

Peter