Oracle Forms

I have a db function that returns a value that I assign to a non-db item in Forms. The function compiles fine in the database, I've granted execute privileges to the forms user, and the form in which it's called compiles fine, but when I run the form and the trigger in which the function is called is fired, I get a ORA-04067 error, and Display_error doesn't show any additional information. My function syntax is as follows:

CREATE OR REPLACE FUNCTION f_method_in_prod(form_smi_field varchar2) RETURN VARCHAR2 IS
cur_smi varchar2(200) := form_smi_field;
cursor smi_lu is
select source_method_identifier from nemi_data.method
where cur_smi = source_method_identifier;
smi_var varchar2(200);

begin
open smi_lu;
fetch smi_lu into smi_var;
close smi_lu;
if smi_var is not null
then
RETURN 'yes';
end if;

END f_method_in_prod;

I've tried calling the function as function_name and as schema_name.function_name in the form and I get the error regardless of the format I use.

I'm using Forms 9.0.4

Any suggestions?

thanks