Serial Number creation problem in S/4HANA 1909 version

Hi All,

I am creating serial number for a material through IQ01 and later on want to create equipment from there.

First I created a material and assigned serial number profile in plant data storage 1 view. Now when I create serial number through IQ01, Stock type, Plant fields are grayed out as shown below. I am not able to input values in to the fields Stock type, Plant .

Thanks

Kumar