The research commissioned by the Scottish Negotiating Committee for Teachers on school support staff (page one) perfectly illustrates the quandary.
Government provides the means, authorities have discretion and schools are left to cry: "Where's our cash?" There must be a better way, but it is difficult to see what it is. The alternative scenario is: government ring-fences funds, schools may end up with money that doesn't suit their plans and the authorities cry: "Where's our flexible friend?"
Nobody pretended the ambitious teachers' agreement, with its complex and varied strands, was going to be easy to implement. And so it has proved.
But it becomes a serious matter if a clear national agreement, signed up to by all parties, is thwarted by the vagaries of local government finance.
The Scottish Executive may claim that the research report is an out-of-date "snapshot" but, as things stand, there is little to stop the missing quarter of the pound;50 million earmarked for support staff becoming an unaccounted quarter of the promised total of pound;100 million.
There is more to this than money, of course: the differing assessments by headteachers and authorities on the impact of support staff on schools shows this is very new territory. But there has to be confidence that funding is secure if impact is to have any chance.