How to fetch data in custom Doctype

I had doc type name Deal, Based on deal, i will create Quotation, i need to fetch deal data in quotation fields.

These data need to fetch in Quotation.

Deal Customization

Even tried deal.lead_name
But still not data fetch from deal to quotation.
How to fetch these datas.

@Mohamed2335 it’s custom_opportunity .

Thanks for the Response,but it not reflect.

still same issue
Also Tried custom_opportunity.lead_name

I did not see you create a Link field in Quotation to select Deal…

Opportunity is Deal Doc type name