I am trying to find all Saturdays within a range(on row 14), and if a
Saturday is detected, then I would like to add the values in the
corresponding row for the Saturday only dates(available in row 16).
After going through the date range, if the total sum is zero, then I
would like to return false.  I also am trying to avoid doing this via
a macro as it should be automatically re-calculated if a cell changes.

Currently I have the cell formatted as follows that will provide a
true or false, if any Saturday is detected with values in the
corresponding row.  I created a IsSaturday function, that seems to be
returning #value.  The result is that the formula always produces the
result of false.

=IF(SUMIF($C$14:$AG$14,IsSaturday(),C16:AG16)<>0, TRUE, FALSE)

Below is the function I have coded:

Public Function IsSaturday(x As String) As Boolean

If Weekday(DateValue(x)) = 7 Then
   IsSaturday = True
Else
   IsSaturday = False
End Function

Is there something I am missing here, or can it be done a better way?

Thanks & regards,
 Enzo