sum of 2 columns not appearing since 1 is blank

[trident]

I have a table with the following information

Staff	Inv Date	Amount	Int/Ext
A	Jul 1 2017	200	I
A	Jul 2 2017	300	I
A	Jul 1 2017	100	E
B	Jul 3 2017	100	I
B	Jul 4 2017	100	I
B	Jul 5 2017	150	I
C	Jul 1 2017	50	E
C	Jul 2 2017	100	E
C	Jul 3 2017	100	E

Based on this table, I made a query to group together Int/Ext and Staff, and their Totals

Staff	Internal	External	Total
A	500	100	600
B	350
C		250

As you can see, there are no totals on row B and C, as there is a blank space. How can I total the B and C, even if it is blank and not zero.

Thank you again for the assistance.

Trident

[RuralGuy]

I believe you should look into the Nz() function.