There are 2 issues here:
This first is DDTS Issue CSCsa02605.
IDS MC was not properly detecting errors during signature updates on the sensors and so was incorrectly stating the install was successful.
The second issue is what caused the error during the installation in the first place. You will need to do more analysis to determine why the upgrade is failing.
The CSCsa02605 has been fixed in the IDS MC 1.2.3 release earlier this month. Upgrade the IDS MC to 1.2.3:
http://www.cisco.com/cgi-bin/tablebuild.pl/mgmt-ctr-ids-app
Once the IDS MC has been upgraded then try re-installing the signature update. If the is an error then IDS MC shoudl report the error and you can then try and determine what is causing the installation to fail.