Can't relate contact to potential

Can't relate contact to potential

Hello

I am creating contact and potential throught api. I can successfully make contact and whole potential data, but can't relate them to one-another. 

Here is my XML for contact:
  2. <Contacts>
  3. <row no="1">
  4. <FL val="First Name">' . $person["name"] . '</FL>
  5. <FL val="Last Name">' . $person["surname"] . '</FL>
  6. <FL val="Email">' . $person["email"] . '</FL>
  7. <FL val="Department">Business</FL>
  8. <FL val="Phone">' . $person["phone"] . '</FL>
  9. <FL val="Mobile">' . $person["phone"] . '</FL>
  10. </row>
  11. </Contacts>';
And part of XML from potential:
  1. <FL val="Potential Name">' . $potential["name"] . '</FL>
  2. <FL val="Contact Name">' . $person["name"] . " " . $person["surname"] . '</FL>
When I make requests with both it makes new contact and new potential but Contact Name in potential is emthy.
(I make contact request before potential one)