To calculate Business Ownership, ResearchPoint multiplies "% Ownership" by "Valuation of the Company". If the Valuation is blank, an amount cannot be calculated. There are a few reasons that the Valuation is not listed in Dun&Bradstreet.
Not all valuations are available in all situations. Sometimes there is not enough data to be able to calculate this. Perhaps the SIC code represents a small industry and there are few business sales in the industry type. That could mean that the ability to generate a more reliable valuation formula for that industry is not going to happen for a while.
The field is reported by Dun & Bradstreet. It is possible that there is nothing there because there isn’t enough data to support a formula that gives reliable/reasonable results. To resolve this, you can always do the legwork to determine the value yourself and fill in that field with the results. Perhaps you will be able to find information online about a sale of that type of company or information about its value. You could also consider reaching out to the Prospect-L listserv to see if others have guidance on what they do in that situation.