Following command will help to enable the IIS 6 for 32 bit applications.
Open a command prompt and navigate to the %systemdrive%\Inetpub\AdminScripts directory.
Type the following command:
cscript adsutil.vbs set W3SVC/AppPools/Enable32BitAppOnWin64 True
you can also use following
cscript adsutil.vbs set W3SVC/AppPools/Enable32BitAppOnWin64 1
to revert
cscript adsutil.vbs set W3SVC/AppPools/Enable32BitAppOnWin64 0