Can't Figure out #Error on Form Footer in Access

[Dilbert99]

I have a data entry form I set up in Access. It is a continuous form, and has a footer which accumulates field totals. I set up my totals with the =sum([fieldname]) in the Control Source property and it was working, but for some odd reason it stopped working and all I get now are #Errors. I've double-checked the Syntax and spelling and don't see any issues. Any thoughts on what might be causing this error?

 

[theDBguy]

Hi. Welcome to AWF! The Sum() function could return an error if any of the data it's trying to total is a Null value. Maybe you could double check to make sure you don't have any Null data? Just a thought...

 

[Deleted member 147267]

Sum with nulls works for me in footer or header of form - whether or not the field to be summed is on the form. At least it does at the moment.
If [fieldname] is a calculated field I would not expect it to work.