I've put together many multi-company product development partnerships. However, as a startup, the other company may not consider you to have enough credibility (longevity, need to pivot to better meet market needs, time for product to reach market) and may not want to expend the time and resources requied to make a partnership work.

The value proposition can be time to market, differentiation as far as a more complete solution, use of sales force and channel or marketing dollars to sell something that is more readily acquired by a customer. As the startup, you gain credibility through the brand of the other company, if it's established, trusted, and well known.

I would need to know more about your particular situation to be able to be more complete in answering this question. Please feel free to give me a call if you'd like to go into further detail.