In reference to the post below, where it says I should increase the version number for older versions to be replaced by newer ones.
http://stackoverflow.com/questions/40603/msi-installer-fails-without-removing-a-previous-install
What I find is, just changing the version number didn't do the job. I had to change the product code also, which I got an option to change through a Message Box just after changing the Version Number.
Is this how it's supposed to be?