Field to get the value and set to value or null:  NEWBUYOUT: Nz([BUYOUT_QUANTITY],[0])

Field to pull value from above field:
CleanNum: [NEWBUYOUT]

Field to do math:
Pull: [WS_QUANTITY]-[CleanNum]

The query shows numbers the report will still error on any [Pull] item that the [CleanNum]is 0 (the original field was null)

As to the other, I appreciate your response and understand this is free help.  The site does send you e-mails every time to view the site, so in wanting to try and resolve this issue, I was viewing the site several times daily and getting two e-mails for each visit.  

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Reply from Richard Rost:

Don't put the 0 in square brackets. Now Access will look for a field NAMED "0" which you shouldn't ever have. It should just be:

NEWBUYOUT: Nz([BUYOUT_QUANTITY],0)

Run that query by itself and make sure all your values are good. THEN run the 2nd query using query 1 for data.