Not too much of information in your question about what issue you are having.
"Anthem" isn't part of the standard ASP.NET. Whomever makes "Anthem" may have their own support forums. You should start looking there for an answer.
I had found that specific questions related to 3rd party is answered more quickly and accurately at respective forums.
Do look at this article, if it helps:
Build an Anthem.NET [AJAX] Autosuggest Textbox[
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