HttpUtility.ParseQueryString(myquerystring) removes = sign from string

HttpUtility.ParseQueryString(myquerystring) removes = sign from string

My exact query string is:
WHERE ( 1 = 1 ) AND (village = 'Amsterdam')
the result is:
WHERE ( 1 1 ) AND (village = 'Amsterdam')
Why ist the first = removed ?
second try :
WHERE ( null is null ) AND (village = 'Amsterdam')
the result is: (second = is removed)
WHERE ( null is null ) AND (village 'Amsterdam')
My environment:
VS2010, ASP.NET 4.0, SQL-Server 2008, unicode8