IBM BPM Standard 7.5.1.1 - Problem importing snapshots into a Process Server

So I've been doing a lot of work with BPM snapshots and scripting recently.

This time around I was looking to install a snapshot to an offline Process Server, as follows: -

$ cd /opt/IBM/WAS/wasadmin1/app/profiles/dmgr/bin
$ ./wsadmin.sh -host processserver.uk.ibm.com -port 43003 -user tw_admin -password passw0rd -lang jython -p /home/wasadmin1/davehay_soap_override.props
wsadmin> AdminTask.BPMInstallOfflinePackage('[-inputFile /home/wasadmin1/LR2R3_1.zip]')

 which (sadly) failed with: -

WASX7015E: Exception running command: "AdminTask.BPMInstallOfflinePackage('[-inputFile /home/wasadmin1/LendingR2R3.twx]')"; exception information:
java.lang.Exception: java.lang.Exception: java.lang.NullPointerException

Want to know what was wrong ?

I was trying to install the actual TWX file, rather than the ZIP file that contains the TWX file ( as generated by BPMCreateOfflinePackage and BPMExtractOfflinePackage ).

What a muppet :-)