argumentexception

Why is ProgressBar.SetValue throwing ArgumentException with valid values?

Why is ProgressBar.SetValue throwing ArgumentException with valid values?
I am using WPF's ProgressBar object, which has a Value property, and I can pass it a constant int or decimal value and it doesn't complain, but if I pass it a float (or int or string) variable value, it barfs an ArgumentException (e.g."Message='0.023