Regarding DFF

Question

Hi all,
i have created a form and a table and registered the table suing ad_dd package.
my requirement is to create DFF on the form so that, i created a procedure and given code for "WHEN_NEW_FORM_INSTANCE" and also for WHEN_NEW_ITEM_INSTANCE after that i deployed my form in Applications when i run Open the form i got the following error message.
APP-FND-00682: Program error: Routine FDFGDC cannot read structure ID field. The developer specified a structure ID column (via the Register Descriptive Flexfields form) that does not exist in this block of this form.
Action: Contact your support representative.
APP-FND-01242: Cannot read value from field STUDENT.ATTRIBUTE_CATEGORY
Cause: The field STUDENT.ATTRIBUTE_CATEGORY could not be located or read.
Action: This error is normally the result of an incorrectly-entered field name string in a trigger, or a field name string that does not uniquely specify a field in your form. Correct your trigger logic to precisely specify a valid field.
can any one tell me How to rectify this error and please give me some information on how to Impament DFF's in a form.
thans in advance,
siddam

Answer 1

the code for when_new_form_instance is
BEGIN
     SRI_DFF_TEST.DFF_PROC('WHEN_NEW_FORM_INSTANCE');
END;
and the package in program units is
PACKAGE BODY SRI_DFF_TEST IS
PROCEDURE DFF_PROC(EVENT VARCHAR2) IS
BEGIN
     IF (EVENT= 'WHEN_NEW_FORM_INSTANCE') THEN
          FND_DESCR_FLEX.DEFINE( BLOCK => 'STUDENT',
          FIELD => 'DFF_TEXT',
          APPL_SHORT_NAME =>
'CUSTOM_APPLICATION',
          DESC_FLEX_NAME => 'SRI_TEST_DFF');
     END IF;
     END DFF_PROC;
END;
in the when_new_item_instance trigger i have given the following code.
when_new_item_instance
DO_KEY('EDIT_FIELD');
thanks for your time and patience,
siddam