Upgrade from 1.6.5.4 ->1.7.0 -> 1.7.1.1 is not supported

ERROR MESSAGES:-
[2011-09-20 10:17:49,023] - [remote_util] [47550853327296] - ERROR - Would overwrite the following files:
[2011-09-20 10:17:49,023] - [remote_util] [47550853327296] - ERROR - /var/opt/membase/1.6.5.4/data/ns_1/default-data/default
[2011-09-20 10:17:49,024] - [remote_util] [47550853327296] - ERROR - /var/opt/membase/1.6.5.4/data/ns_1/default-data/default-0.mb
[2011-09-20 10:17:49,024] - [remote_util] [47550853327296] - ERROR - /var/opt/membase/1.6.5.4/data/ns_1/default-data/default-3.mb
[2011-09-20 10:17:49,024] - [remote_util] [47550853327296] - ERROR - /var/opt/membase/1.6.5.4/data/ns_1/default-data/default-2.mb
[2011-09-20 10:17:49,024] - [remote_util] [47550853327296] - ERROR - /var/opt/membase/1.6.5.4/data/ns_1/default-data/default-1.mb
[2011-09-20 10:17:49,025] - [remote_util] [47550853327296] - ERROR - ERROR: upgrade failed for bucket: default
[2011-09-20 10:17:49,025] - [remote_util] [47550853327296] - ERROR - dpkg: error processing membase-server (--install):
[2011-09-20 10:17:49,025] - [remote_util] [47550853327296] - ERROR - subprocess installed post-installation script returned error exit status 1
[2011-09-20 10:17:49,025] - [remote_util] [47550853327296] - ERROR - Errors were encountered while processing:
[2011-09-20 10:17:49,026] - [remote_util] [47550853327296] - ERROR - membase-server
[2011-09-20 10:17:49,026] - [remote_util] [47550853327296] - INFO - (Reading database ... 53283 files and directories currently installed.)

[2011-09-20 10:17:49,037] - [remote_util] [47550853327296] - INFO - /opt/membase/bin/mbdbupgrade /var/opt/membase/1.6.5.4/data/ns_1/default /var/opt/membase/1.6.5.4/data/ns_1/default-data
[2011-09-20 10:17:49,037] - [remote_util] [47550853327296] - INFO - mbdbupgrade pid: 22871
[2011-09-20 10:17:49,037] - [remote_util] [47550853327296] - INFO - mbdbupgrade err: 256
[2011-09-20 10:17:49,037] - [remote_util] [47550853327296] - INFO - Processing triggers for ureadahead ...