Cold calling people on LinkedIn probably wont prove all that successful but it can't hurt.
The real question is do you have anything built yet? Do you have domain expertise in the space you are targeting?
In lots of cases enterprise software for niche scenarios is born out of a consulting engagement: Company A contracts you to build them a system for tracking widgets. You do so and get their permission to use that software in other projects. Company B wants widget shipment calculation software so you go to them and say 'I know about widgets, we built this widget tracking thing and we can add shipment calculation to it'. That is how the ball gets rolling.
Most software in this kind of space is packed full of features and rules that are not easily just spawned out of thin air - it usually takes many man years of development.