PL/SQL: ORA-00932: inconsistent datatypes: expected NUMBER got -

I want to generate XML from some of my tables and stored as a CLOB file. When i try to run my query, it throws some errors. But I can't able to find where my mistake is. Anyone help me to solve my problem.

This is my Query:

CREATE OR REPLACE
PROCEDURE "test_Dinesh_page_1"
(
i_LRE_PeerGroup_ID IN number
)

as
l_outxml clob;

 BEGIN
    with xmldata as (
      select es.d_reportentity_id
      , es.d_reportperiod_id
      , es.avgoralhealthscore
      , es.ScorePercentile
      , es.CostPMPM
      , es.topClaimPercent
      , es.topClaimState
      , l.LKP_reportEntity_PeerGroup_id
      , l.d_PeerGroup_ID
      , rp.EndYear
      , rp.EndQuarter
         from   f_ReportEntityScore es
          join  LKP_ReportEntity_PeerGroup l
              on es.d_reportperiod_id = l.d_reportperiod_id
              and es.d_reportEntity_id = l.d_reportEntity_id
          join  d_reportPeriod rp
              on es.d_reportperiod_id = rp.d_reportperiod_id
          where l.LKP_reportEntity_PeerGroup_id = i_LRE_PeerGroup_ID      
    )
    select xmlelement("ReportPage"
      , xmlelement("PageNumber",1)
      , (select xmlforest(
          cast(round(x.avgoralhealthscore,0) as int) as "DentalScore"
          , x.ScorePercentile as "DentalREINPercentile"
        ) -- END xmlforest
        from xmldata x
        where x.LKP_reportEntity_PeerGroup_id = i_LRE_PeerGroup_ID
      )
    )   
     into l_outxml
    from dual;
    dbms_xslprocessor.clob2file(l_outxml, 'GLOBALSTRATEGY', 'GlobalStrategies.xml', nls_charset_id('UTF8'));
end;

The error code is:

PL/SQL: SQL Statement ignored
 PL/SQL: ORA-00932: inconsistent datatypes: expected NUMBER got -

Thanks in advice.