WorksheetFunction.IsNA (Excel)

Checks the type of value and returns True or False depending on whether the value refers to the #N/A (value not available) error value.

The value arguments of the IS functions are not converted. For example, in most other functions where a number is required, the text value 19 is converted to the number 19. However, in the formula ISNUMBER("19"), 19 is not converted from a text value, and the IsNumber function returns False. The IS functions are useful in formulas for testing the outcome of a calculation. When combined with the IF function, they provide a method for locating errors in formulas.

IsNA (Arg1)

Arg1: Value - the value that you want tested. Value can be a blank (empty cell), error, logical, text, number, or reference value, or a name referring to any of these, that you want to test.

Dim booIsNA As Boolean
booIsNA = WorksheetFunction.IsNA(Arg1:=)