Altiris agent not installed

Hello 

We have altiris 7.1 installed systems... We have uninstalled 7.1 altiris agent by using command line

C:\Program Files\Altiris\Altiris Agent\AeXAgentUtil.exe /uninstallagents /clean 

after successfully uninstall altiris agent we tried to installed altiris 7.6 agent on the same system by using Push method / Manuall installation method / Pull method but agent not installed.

If we push through console aexagent.ext got copied but not executing. When we double click and trying to run we face error.