Hello world!

I observe a strange behaviour for the multi-threaded calculation in Excel
2007 with my XLL.
I have 2 functions A and B exported by the xll. They are registered as
threadsafe.
A is registered with R$.
B is registered with RR$

The function B depends on the result of the function A.
On a worksheet, I can decla
- =A() in cell A1
- =B(A1) in cell A2

When I disable multi-threaded calculation, =A() is executed before =B(A1)
because B depends on the result of =A().
But, when I enable multi-threaded calculation, Excel runs A and B on
different threads. The function B failed with xlretUncalced when it called
xlCoerce. Excel launches again B after the execution of A. Why does excel
calculate B and A at the same time at the beginning?

Thanks for any suggestions.