plsql - "EXECUTE IMMEDIATE" command issue in Oracle -

i'm trying execute block inside procedure...

 schema_nm := 'devl';  plsql_block:='begin ' || schema_nm || '.lic_pkg.remove(:x, :y); end;';  begin      execute immediate plsql_block using  in_val1,in_val2;           end;  

when try execute above see error..

ora-06550: line 1, column 7: pls-00201: identifier 'devl.lic_pkg' must declared ora-06550: line 1, column 7: pl/sql: statement ignored 

please let me know if have come across kind of error...

thank in advance help.