Pass String Value as an Parameter in Report Layout

Dear Experts,

As per our requirement, we develop an Bill of Material Report in Crystal Report.

We develop an Report as an Layout.

I used Product Code Number as an Parameter Value.

But my problem is when i select that layout from Bill of Material Form.

It will always ask for Product Code Number as an parameter.

I also set parameter properties as an "Do not Show" but can't work.

as per my opinion, i passed String value as an parameter so,

it will always ask for enter parameter value.

I can't find out the solution.

Please help me.

Thanks & Regards,

Nishit Makadia