'windows-1255' is not a supported encoding name

hi,

my code is:

using (StreamReader reader = new StreamReader(fileStream, Encoding.GetEncoding("windows-1255")))

but i get the exception "'windows-1255' is not a supported encoding name" why is that?

and how do i read a file in the "windows-1255" encoding? (Hebrew)

thank you very much in advance

jony