Error after installing TOPO 24k to Micro SD card in handheld 64st

I downloaded TOPO U.S. 24K Southwest to an SD card in my 64st.  After downloading to the SD card, I got an error in Basecamp stating there was a problem with the 24k TOPO map.  After clearing the error message, the 24k TOPO map doesn't show up on the dropdown in Basecamp.  How do I make this work?