error when trying to save to an xlsx file

I have an application (pb12.6 classic)

When I execute the command

if (dw_humboldt_out.SaveAs(s_path,XLSX!,TRUE,EncodingANSI!) < 0) then

it works fine on my machine... but, of course I have pb12.6 development installed

I have a person, who simply has the application installed, and it fails to create the file

Any ideas?

we are both running windows 7.... excel 2010