My guess is that when uninstalling Flexnet, Windows service has not been removed and now installer tries to update existing installation instead of performing a new one, because it "sees" the service in the registry.
Try to delete Flexnet service (usually lmadmin_ptc) and restart installer, usually it helped.
To delete lmadmin_ptc service, you can run command prompt as an administrator and use command
sc delete lmadmin_ptc
Of course, first check if the Flexnet service exists and if that's the correct name.
