It could be J2ME has no support for basic authentication, I might be wrong. If you want to try just setting the authentication header in the request yourself you'll likely need a different header then what you're using.
From the rfc:
To receive authorization, the client sends the userid and password, separated by a single colon (":") character, within a base64 [7] encoded string in the credentials.
[...]
If the user agent wishes to send the userid "Aladdin" and password "open sesame", it would use the following header field:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
So just create the string "User:Password", base64 encode it and then call setRequestProperty("Authorization", "Basic "+ encodedUserAndPass)