Slice Facts based on UI events

OK.  I've done that.  The formula for the measure is: 

FocusDate = if(
                                 selectedvalue(DateFocus[ID]) = 1, 
                                 min(FactInternetSales[OrderDate]),
                                 if (
                                                  selectedvalue(DateFocus[ID]) = 2,
                                                  min(FactInternetSales[DueDate]), 
                                                  min(FactInternetSales[ShipDate])
                                    )
                        )

the aggrigation error went away.  Indeed the measure was added to the table with no error. 

Now - when I took the calculated column off of the datamodel, the graphic errored because a data field on the axis was then invalid.  My column chart now has only one column - the value being all time.  When I drag a real date (say Due Date) to axis, the visual breaks into multiple columns as I expect and want.  I remove the real date from Axis, and it goes back to one coilumn - again as I expect.  I drag the Focus Date measure to Axis and - nothing.  No error message.  It just does not drop.  The boarder of the axis does turn yellow telling me it expects me to drop.  But when I release the mouse button - it goes back to Add data field here.

How can I put a measure on the axis of a visual?