Http.open and opera problem.

hi.

Im having a problem with opera and http.open() command.

the code is : ( Names/addresses changed )
{
var 1 = "1";
var 2 = "2";

http.open("GET","http://www.something.net/cgi-bin/something.cgi?attribute1=" + var1 + "&attribute2=" + var2 + "&attribute3=3", true);

http.onreadystatechange = handleHttpResponse;
http.send(null);
}


Opera's (version 8.5) javascript console produces this error:
Type mismatch (usually a non-object value used where an object is required)

and it refers to the http.open command.

This syntax works in FF and IE.

any ideas?