Step 10 of 14 Mailbox Role Error

I keep getting the following error:

Error:
The following error was generated when "$error.Clear();
          if (!$RoleIsDatacenter)
          {
            $arbUsers = @(get-user -Filter {lastname -eq "MSExchApproval 1f05a927-3be2-4fb9-aa03-b59fe3b56f4c"} -IgnoreDefaultScope -ResultSize 1);
            if ($arbUsers.Length -ne 0)
            {
              $mbxname = $arbUsers[0].name;
              $mbxs = @( get-mailbox -arbitration -Filter {name -eq $mbxname} -IgnoreDefaultScope -resultSize 1 );
              if ( $mbxs.length -eq 0)
              {
                $dbs = @(get-MailboxDatabase -Server:$RoleFqdnOrName -DomainController $RoleDomainController);
                if ($dbs.Length -ne 0)
                {
                  enable-mailbox -Arbitration -identity $arbUsers[0] -database $dbs[0].Identity;
                }
              }
            }
          }" was run: "Active Directory operation failed on servername.domain.com. This error is not retriable. Additional information: An attempt was made to modify an object to include an attribute that is not legal for its class.
Active directory response: 0000207D: UpdErr: DSID-03151222, problem 6002 (OBJ_CLASS_VIOLATION), data -1814126740".

When I go into ADSI Edit:

Configuration > CN Services > Microsoft Exchange > OrganizationName >  Administrative Groups > Exchange Administrative Groups > Databases

I have 3 Mailbox Databases listed. Should I delete 1 or all of them?