Our customer encountered the following error when they did Kerberos authentication using Java GSS-API of jdk 6 on Windows x64(Windows 2008 R2)

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Error calling function Protocol status: 1312
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It seems the error message came from w2k_lsa_auth.dll. And their test program single signon is similar to the code shown in Figure 7 at the page below.

http://docs.oracle.com/javase/6/docs/technotes/guides/security/jgss/single-signon.html

1. What does this error mean?
2. Under what kind of conditions this error occurs?

In jdk7 the error message only shows with debug mode(-Dsun.security.krb5.debug=true). In jdk6 this error message is not supposed be output generally(non debug mode), right? The customer requested us to suppress this message output in jdk 6 like what to do in jdk7