HELLOAGAIN! is solid entertainment because Linden Waddell clearly has great reverence for Allan Sherman’s material and genuine stage presence. Many of the song parodies she performs, like the forgotten “Chopped Liver” (a dead-on spoof of “Moon River”), weren’t among Sherman’s most successful but they work wonderfully with a live audience. Never heard of Allan Sherman? No matter; nor had many of the young people in the audience (apart from maybe “Hello Muddah, Hello Fadduh”) but they clearly had a great time.