[Zope] Parameter in ZSQL

Hello All here's the problem my Zope 2.2.0 is running on win98 my Database is a MySQL I created a ZSQL method named ShowProduct with parameter product_id the template as follows : select * from products where <sqltest product_id type=string> why can't I call the ZSQL method directly (without using the GET/POST variables)? I try to call it like this <dtml-let product_id="1"> <dtml-in ShowProduct> ...(i would like to insert some of programs here if this is working) </dtml-in> </dtml-let> it always returns error like this Error Type: Bad Request Error Value: ['product_id'] can anyone help please? is there any workaround for this? TIA -IGUN- ICQ:1474584