re-installing service desk plus

re-installing service desk plus

while i am trying to reinstall the service desk plus build 7611 i am getting the following error.
 
"A previous version of MAnage engine Service desk plus was found in this machine...."
 
but my mchine dosent have any version. is there any specific registry keys that needs to be removed before re-installing...
 
any help on this is highly appreciated.....
 

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