I need to remove the zero when the answer comes back ZERO. I need the field to be blank. Nothing in it. Thanks in advance for your help.

You could set the FORMAT property of your field to #,###

This would display blank when zero and 234 or 1,234 (for example)

Is it a calculated field?
Try iif(Sum([Field4) = 0, Null, Sum([field4))

Make sure there is no default of 0 on the form. Also check the table to make sure there is no default of zero on the table.