SQL & PL/SQL

How to run a function with out parameter in the execute immediate statement?

declare
   vRunFunctie   varchar2(100) := 'startfunction';
   vParmIn1      varchar2(100) := 'AAA';
   vParmIn2      varchar2(100) := 'HHH';
   vParmOut1     number;
   vParmOut2     varchar2(100);
begin
   --
   execute immediate 'select '||vRunFunctie||'('''||vParmIn1||''','''||vParmIn2||''',:vParmOut2) from dual' into vParmOut1 using vParmOut2;
   --
   dbms_output.put_line('vParmOut1['||vParmOut1||']');
   dbms_output.put_line('vParmOut2['||vParmOut2||']');
end;
/

getting error: ORA-06572 Function startfunction has out arguments

the statement looks like this in pl/sql:

vParmOut1 := startfunction(vParmIn1, vParmIn2, vParmOut2);
--vParmOut1 := startfunction('AAA', 'HHH', vParmOut2);

Thanks.
L.

update:

You are not using bind variables with your dynamic code. That is a major mistake and the #1 reason for poor database performance.
It is a fundamental flaw in programming to design a function that includes output parameters. This is simply and plainly wrong.
Output parameters are also not supported by the SQL language - it does not support "procedure" like code units and call methods. 

I know the function should not have out parameters. But its programmed this way allready..