Does Approver have authority ?

Pos submitted by one of the user getting into document manager failure we have examined various factors

1. Other users with same responsibility not facing error

2. Same approval hierarchy followed by number of users

3.Pos are auto created from PRs so no problem with the charge account

4. examined the error using diagnostics tools shows error at

Error says Does Approver have authority ?

Can any one reply what other probable error could have occured