I am trying to make sure a string reads am or pm before I let the variable be passed to a check routine. I used this but its not working right.

Code:
        If alrmampm <> "AM" Or alrmampm <> "PM"  Then
            MsgBox("Enter a valid time.")
            ampmcb.SelectAll()
            Exit Sub
        End If

But I used the same comparison format here, and it works fine.

Code:
        If alrmhours = "" Or alrmhours < 0.ToString Or alrmhours > 12.ToString Then
            MsgBox("Enter a valid time.")
            hourscb.SelectAll()
            Exit Sub
        End If

        If alrmminutes = "" Or alrmminutes < 0.ToString Or alrmminutes > 59.ToString Then
            MsgBox("Enter a valid time.")
            minutescb.SelectAll()
            Exit Sub
        End If
I'm probably going about this the wrong way, but until I learn the vb syntax better I have to work with what I know. So could someone tell me why that expression isn't working?