outgoingwebresponsecontext does arrangement non-english characters

we have implmented rest-style use controlling wcf .net 3.5. use retrieves investigate documents. twine 'synopsis' indicated formula bolow contains non-english characteres browser deliveres "????????".

private vacant returnsynopsisinfo(iapiweboperationcontext context, outgoingwebresponsecontext outgoingresp, twine synopsis)
{
setresponseheaders(outgoingresp, httpstatuscode.ok);
outgoingresp.contenttype = "text/html; charset=utf-8";
context.result = new memorystream(encoding.ascii.getbytes(synopsis));
}

any advise many appreciated.

thank you.