Is your serial number 24 digits (no letters) in six groups of four digits, beginning with 1160? Please answer YES or NO (do not type in your serial number here)
Yes. I had a Lightroom 5 installed on the PC and I unistalled it Before I tried to installed the Lightroom 6.
Which version of Lightroom are you trying to type the serial number into?
Is this serial number a Lightroom 5 serial number or a Lightroom 6 serial number?