Return block stock to vendor

Hi,
I want to return defect stock to vendor. The stock already transfer from unrestricted to block stock.

As per I had learn, we need to issue PO return (ME21N) then using MIGO to transfer by using Goods Issues & Movement type 124.

But when I want to do the transaction had pop up [Purchase order ****** does not contain items for a stock transfer].

Why i can't do the transaction?

Anyone please help me