Syntax question concerning an if statment

Ok say I have a list of numbers that I want to make sure do not equal each other can I do it like this:

If (num1 <> num2 AndAlso num3 AndAlso num4) Then
If (num2 <> num3 AndAlso num4) Then
if (num3 <> num4) Then
boolVariable = true
End If
End If
End If

So far this method work most of the time, but sometimes It fails to catch duplicates.