Confusing Chr$ explanation

[PhilOfPerth]

From the WIKI:        the CHR$ function returns the character associated with a certain character code as a STRING
                 and:        Valid ASCII code% numbers range from 0 to 255

So why does this not work:

For a = 129 To 255
Print a; Chr$(a)
Sleep 1: Cls: Next 

    

What output are you expecting, and what output are you getting?

 I WAS getting nothing for a second or two, then a giant symbol, then crashed; But now, I get what I expected, each char in turn with its code. 
I suspect there was something hanging in my computer that shouldn't be there, but I had nothing else open. 
Sorry, looks like my problem!