Problem calling user defined function from Forms 4.0 Trigger

Problem calling function from within Forms 4.0 Trigger

I am trying to call a user defined SQL function from within a trigger in Forms Version 4.0. The function is called preferred_name, and returns a VARCHAR2 string (a name) given various input parameters. Testing the function from the sqlplus command line yields

SQL> select csv_user_oracle.preferred_name('','','','Mr','Richard','James', 'Rich','Tinker','N','N','N','N') from dual; Press Return to continue...
CSV_USER_ORACLE.PREFERRED_NAME('','','','MR','RICHARD','JAMES','RICH','TINKER','

        select csv_user_oracle.preferred_name('','','','Mr','Richard','James',
	'Rich','Tinker','N','N','N','N') into result from dual;

:MEMBERSHIP.DISPLAY_1 := result;

END; The error obtained is

Error 356 at line 4, column 113

        'DUAL' must name a table to which the user has access.

I have checked that there are no return characters in the returned text. I am confused by the message. I have tried specifying sys.dual but to no avail.

Can anyone help ?

Thanks in advance

Richard

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R.J.Tinker_at_csv.warwick.ac.uk