MCH5003, scalar error - ILE RPG

Question

Called program entry:

dcl-pi PGM1;
  choice uns(3) const;
  returnCode likeds(returnCodeTpl);
  parameterPtr pointer const options(*nopass);
  parameterPtr2 pointer const options(*nopass);
  parameterPtr3 pointer const options(*nopass);
end-pi;

Caller program:

document.field1 = 'EL';
document.field2 = 'T';
document.field3 = 2780;

PGM1(1:returnCode:%addr(document));

document definition (on called):

dcl-ds document_ qualified based(parameterPtr);
  field1 char(2);
  field2 char(1);
  field3 packed(7:0);
end-ds;

document definition (on caller):

dcl-ds document qualified inz;
  field1 char(2);
  field2 char(1);
  field3 packed(7:0);
end-ds;

Called program then process the document DS, calling an exported procedure:

select;
  ...
  when (1 = choice);
    myProc(document_);
  ...
endsl;

myProc definition:

dcl-proc myProc export;

  dcl-pi *n ind;
    document likeds(document_) const;
  end-pi;

  dcl-s i int(5) inz;

  exec sql                    <--- Error appears there
    select count(field1) into :i from myFile
    where
      field1 = :document.field1 and
      field2 = :document.field2 and
      field3 = :document.field3;

  ...

  return i > 0;

end-proc;

myFile fields equal in types document fields.

The error a keep getting is MCH5003 - scalar error. The length of the invalid scalar operand is 128. Debug stop over the exec sql clause.

I really can't figure out what it is!

Answer 1

In the end it was a parameter passing error.
Before the call to PGM1, another call to PGM2 was passing the second out of eight parameters as char(91) instead of char(500).
I didn't see it because it was defined as likeds(), and that DS was supposed to be 500 bytes long.

Thanks anyways @Charles.