Nintex form - approver must be the same person

on the control can you have appearance > enabled > expression

and expression to make use of this function?

Returns true if the current user is the same user specified in the string value.
fn-IsCurrentUser(string loginname)

You could pass in the approver of section one?

Thanks Cassy 

So for the return of true/false - what happens? If its false does the error message show?

your expression for the control being enabled equates to the outcome of that expression.

i.e. if person is approver 1 - enabled = true

if person is not approver 2 - enabled = false

Hi 

I don't seem to have the expression field. I tried you suggestion in the validation, but no luck.

in the above - under appearance and enabled - choose dropdown and choose expression

Many thanks  it works!