Is addition supported in queries?

you answered this yourself in THIS post not so long ago, I think you may need to remove the brackets and check that the field types are the same in the database.

I just set up a quick table od 4 fields, a,b,c,d with random figures in each, each field was and integer.

I did a quick sql query like this

when I built the page it worked, so i tried it with brackets like you have, and it still worked.

I put no quotes around the alias.

HTH

In MySQL use backticks to wrap field names:

As it turns out it is related to two of the monetary fields being set to "NULL". I edited the fields to "NOT NULL" and created a default value of 0.00 for the fields that are not required to be filled (since we don't always have 3 forms of payment for an adoption). The addition is working fine now.
I guess since my report was an afterthought to the initial development, the "NULL" slipped my melon. I kept thinking if the field was null, the math would just do something like add a zero value. How soon I foget that null hoses up so many things.

It has caught me out loads of times.

Just a thought. I found it easiest to control everything from one place. So I make all my fields defined as Null.

Then I just control the required with PHPRunner.
I got caught once defining it as NOT NULL with a 0.00. Then when saving a record with a no value for the number on it would not save and just throw an error. CANT SAVE value is NULL. I found PHPRunner returns a NULL to the database if there is no value in the form field.
So only my primary key is NOT NULL.
I dont know if this is the best way, but hey, stopped those errors, and it is nice to use PHPRunner to take care of the required and formating.
Just a thought.