Shopify get Metafields From GraphQl Using Store front Token

[harSHT_dev1798]

I have created a private app , created a store front token front from there. 
But When i tried to get Metafields from the Api , It Returned empty 

query { productByHandle(handle: "the-t-shirt") { metafields(first: 5, namespace: "instructions") { edges { node { key value } } } } }

But when i tried the Rest api it gives me response .