Installation failed with issues in python

I have a cluster of four nodes, one master and three data nodes, CentOS 6.5. Install using Amabri 1.7 from an Ambari master server. Passed all checks at Confirm Hosts but failed installation with lots of warnings and failures on all four nodes. Mainly most of the warnings and errors were caused by this:
Traceback (most recent call last):
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-INSTALL/scripts/hook.py”, line 38, in <module>
BeforeInstallHook().execute()
File “/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py”, line 122, in execute
method(env)
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-INSTALL/scripts/hook.py”, line 28, in hook
import params
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-INSTALL/scripts/params.py”, line 20, in <module>
from resource_management.libraries.functions.version import format_hdp_stack_version, compare_versions
ImportError: No module named version

Another one is:
stderr:
Traceback (most recent call last):
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-ANY/scripts/hook.py”, line 34, in <module>
BeforeAnyHook().execute()
File “/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py”, line 122, in execute
method(env)
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-ANY/scripts/hook.py”, line 26, in hook
import params
File “/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-ANY/scripts/params.py”, line 117, in <module>
namenode_opt_permsize = format_jvm_option(“/configurations/hadoop-env/namenode_opt_permsize”,”128m”)
NameError: name ‘format_jvm_option’ is not defined
Error: Error: Unable to run the custom hook script [‘/usr/bin/python2.6′, ‘/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-ANY/scripts/hook.py’, ‘ANY’, ‘/var/lib/ambari-agent/data/command-61.json’, ‘/var/lib/ambari-agent/cache/stacks/HDP/2.0.6/hooks/before-ANY’, ‘/var/lib/ambari-agent/data/structured-out-61.json’, ‘INFO’, ‘/var/lib/ambari-agent/data/tmp’]

I followed the installation guide carefully and that was not my first installation using Ambari! Any help is very much appreciated.