Need to change field validation in control

Hi Experts,

I'm stuck with trying to help a client who a prior developer for us wrote an application.  It has been years since I did web dev, so forgive what might seem obvious.

There is data validation being performed at the field level.  I know it is the field level since when you exit the field, a negative number changes to a positive, and any formating ($,.) are removed.  The client now needs to allow negative numbers, and I just can't figure out where to make the change.

I'm using VS2005, and the app is in C#.  The control being used is, I believe, Infragistics' Datagrid.  I've been through any property page I can find and looked at the code behind it, but I just can't find where any validation is being performed.  Am I looking in the wrong place?  The closest I could come to something looking like validation is: DataBinder.Eval(Container.DataItem,"amount", "{0:#,0}").

Even after making the change, I may need some help pushing this out, as my prior experiences just required saving Notepad!!