Hm, one thing I can ask is if your viewing a topic or something. If your viewing a topic, you'll see a "Post Reply" button in the prosilver style, where-as the subSilver2 style has it when viewing a topic.
Do you perhaps have a test user that we could possibly use to see? Under the prosilver template, you should be able to see the New Topic button if you view the forum, but not in a topic.
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