Four Salt/Hash errors?

Hello
I am getting four errors in some Salt/Hash code I picked up from a MSDN Web page. All four errors relate to 'SaltValueSize' in the code, as in:
Dim saltValue As Byte() = New Byte(SaltValueSize - 1) {}
Dim binarySaltValue As Byte() = New Byte(SaltValueSize - 1) {}
Dim valueToHash As Byte() = New Byte(SaltValueSize + (encoding.GetByteCount(clearData) - 1)) {}
binaryPassword.CopyTo(valueToHash, SaltValueSize)
In all four cases, SaltValueSize is underlined in blue: 'SaltValueSize is not declared'. But isn't it declared in the first error above?
The Salt/Hash code is in my Login.asp.vb file which also has other code in it related to my Login form, and which is preceded by
Partial Public Class LoginPage Inherits Page I am not sure if 'Partial Public Class' should be changed on account ...