Forms :: Design Time Insert And Update Allowed For Block

I create databalock - LC_REQ_PO_ITM_DTLS...In design time Insert and update allowed for that block - YES. While i execute query, i write procedure like this

GO_BLOCK('LC_REQ_PO_ITM_DTLS');
EXECUTE_QUERY;
SET_ITEM_PROPERTY('pb_item_cd', enabled, property_false);
SET_BLOCK_PROPERTY('LC_REQ_PO_ITM_DTLS',INSERT_ALLOWED, PROPERTY_FALSE);
SET_BLOCK_PROPERTY('LC_REQ_PO_ITM_DTLS',UPDATE_ALLOWED, PROPERTY_FALSE);

but when i press execute button , then data comes properly on that bloack..but i click on that block, error comes like this - 'You can not create record here '.and data disappearing..