There's an old adage, which each new crop of entrepreneurs needs to re-learn: Distributors take orders; they don't "sell". "Distributors", in this sense, includes other companies' saleforces that are going to sell your product. What this means is that is, distributors don't/can't pro-actively market and sell anything that end-users don't already know about and want. For a successful distribution relationship, customer demand must already exist or be generated by the maker of the product or provider of the service being distributed.
That's the good news.
The bad news: distributors completely, really, totally, absolutely don't/can't successfully sell/distribute a product (or service, or combination) that is (1) new, so requires educating the end-customer, (2) requires training of the distributor's salesforce to understand, (3) isn't immediately easy to sell.
Entrepreneurs, if any one of the above 3 attributes is true of your situation, you will be disappointed in any distribution relationship you enter. This is always true, notwithstanding the protestations to the contrary by savvy distributors who've heard the old saw and are smart enough to try to pre-emptively deal with the concern.
Especially for startups, with limited sales, marketing and distribution resources, it is very tempting to believe that "this distributor" is different.
It never is. Beware.