I can not get the range Union operator to work with the Workday
function. See for example row 5 in the following:

A B C D
1 Demonstration that Union operator does not seem to work with WORKDAY
2 function while the same expression does work with the SUM function.
3 2-Apr-02
4 37349 =WORKDAY(B3,1,$B$9:$D$10)
5 #VALUE! =WORKDAY(B3,1,$B$9:$D$9,$B10:$D10)
6 224830 =SUM($B$9:$D$9,$B$10:$D$10)
7
8 Holidays: In the following row, enter the common holidays after Apr
2, 2002 in successive cells.
9 20-May-02 28-Jun-02 1-Jul-02
10 17-Sep-02 23-Sep-02 24-Sep-02
11 Vacations: In the above row, enter the vacations

The same problem occurs with the Networkdays function.

On the other hand, the Sum function works with the same Union
expression, as shown by row 6.

Any explanations or solutions?

Thanks for your help.

Regards,