Can't designate this person as a beneficiary

Hello,

We can't evaluate Salary Change Life event due to an error which is

"You can't designate this person as a beneficiary.  The relationship with the participant is . The plan's designation setup doesn't allow participants to designate beneficiaries of this relationship type. The name of the plan is Basic Life and AD&D. The name of the option is Elect."

In which it does not provide what specific relationship type is referring to.

Kindly see screenshot for your reference.