Applying a traditional consumer approach, aka in-person interviews or even surveys, to businesses is lack of incentive. IMHO most survey results you see, that use commercial firms as the respondents, typically product a consolidated report that is provided for free back to the company when done. If they want the entire report they still have to pay. Consumers who participate in these types of things always receive an incentive or spif, most of the time in cash, sometimes in gift cards (but less effective).
So if you want businesses to participate what is their incentive? x% of an initial engagement, free upgrade to next major release, free tech support for 6 months, etc.
What is the hook?