You might try using the soft-start feature to see if that helps. Have you looked at the output? According to the data sheet these devices current limit using "hiccup" mode, in other words, they don't shut down completely, but 'start' and 'stop'. You should see this on the output, which would indicate that it is, in fact, going into current limit mode. If you just see a flat zero volts, then there might be something else going on.
Stupid question: Can your battery supply the required power?