Hello Terri,
Please ensure that the amplifier is on. There is a ON/Standby light on the amplifier and it should be green. You also want to verify that your audio output is set to Promethean USB Audio. There is an article on our knowledge base at www.prometheankb.com, select your region/language,in the search box type in 10436. The title of the article is "How do I change my computer audio settings to Promethean USB Audio?" (case# 279111)
Thanks!