Queries :: Setting Zero Value In Crosstab Query

I have a crosstab query to summarise the counted string values from another query: E.g.;

TRANSFORM Count(Table1.Viable) AS CountOfViable
SELECT QryTable01.productName
FROM QryTable01
GROUP BY QryTable01.productName
PIVOT Table1.Viable;

As there are some null values returned (ie blank cell in the pivot table)

I used the Nz function to make this zero but when the query results are used in a report I want to add the rows to get row totals... but the result is as if they were string values;

So if I add a text box in the report with = [viable] + [Not viable]
t
Then the report row with the values:

Viable Not viable
14 12
displays as 1412

So how do I add the values in the rows???