I have a report with a sub report, I have added a text box to the report which adds the values from one field in the report to one in the sub report.

I am trying to add a total of this text box to the footer but I keep getting an error #

I am suring I am doing something reasonable basic wrong but I'm stuffed if I can work out what it is.

Could someone please put me out of my misery

Can you post a screen shot, or post your db so that we can see what you mean?

Also, can you explain more? Like, this text box that the sum is in, where is it? Main form or subform? I am having trouble visualizing what you are trying to accomplish.

Totals act on the Recordset fields, not the Report Controls.
You need to generate the field that is to be summed in the Record Source query where it can be totalled.