Sorry it didn’t work out, but you totally took the right (textbook!) approach — I’m sure it’ll work out eventually.
I’m wondering whether you guys looked into the express logistics market: this was one I was very active (and solving the very same problem — minus the smartphone and all of today’s gadgetry) back in 2002–2007 and I would assume your solution would work there too, with the basic difference that (a) picking up an extra parcel (or three) on the way would entail much less of a headache for the driver(s) and (b) that the routes being significantly shorter, means there is much more of an incentive to pick extra loads.
Then again, margins may be much thinner, so perhaps not as profitable.
Be that as it may, best of luck in your next venture!