[AccessD] Query Problem

So, I'm having a bit of an issue w/a small A2010 program I recently wrote. There are a couple of issues, but one, which I thought would be a simple one, has really ticked me off today. 
 
There are several blank records that need to be gone. This is actually a 2 part problem, because some of them (11) are completely blank, but the majority of them (24) were assigned voucher numbers, but have no other data.
 
I think I understand the latter...I assign that number immediately, so if someone clicks to add a new records and does not, or maybe they're hitting the button twice...and I did not have any validation for that event...then I could see a record number w/out any data. But, given what I just said, I do not understand having a record w/no voucher number or data. 
 
Anyhow, having said all of this, what I really want to do right now is to week out those records...get a list, using a query, before deleting them...to make sure my numbers come out right. I figured this was going to be as simple as either putting IsNul(field) in the criteria section...to be sure I was actually going to do 4 fields to be sure....or check for = "".  But, neither of these is working and I'm getting 0 records. 
 
I surely must be forgetting something...making a bone head move somehow. Can someone please set me straight?

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