I think you've zero'd in on it.
It is definitely occuring only the moment I click to the second tab, all other factors independent.
I was thinking it is something about the tab control action that broke it.
Is there anything unique about a tab control? The NZ function may not apply correctly??
And yes, googled and true. It's from Greens site.
Unfortunately I cannot zip a copy, it's a government big data project with tens of thousands of peoples wages, addresses, names etc. Nothing evil, this is where the ALIS wage & salary site gets its data.
But yeah.. weird form and old code.