Renewing your driving license online in Dubai

When registering online for license renewal, the form asks you for "Traffic File Number" which is on car registration cards, or milkiya, if you will. If you don't have your own car, you cannot register. When I called the helpline, they first told me I could not register if I didn't have my own car. Then I called again to ask if I could register on someone else's car registration from my family. They said yes. Then when I tried to do so, it didn't work. It said "Traffic File Data incorrect". Phooey.