Error: "Incorrect credentials. Try again." when logging into NetScaler Gateway

Users fail to log on to NetScaler Gateway with the following error: "Incorrect credentials. Try again." Log on through StoreFront is successful. From /tmp/aaad.debug, the following is the logon failure message: /usr/home/build/rs1011296/usr.src/usr.bin/nsaaad/../../netscaler/aaad/ldapcommon.c341:...