Licence activation isnt working

Hi all.
ive been directed here by sales, to try to find out why the pro licence i purchased 2 years ago, will not work on my new pc.
I haven’t been able to use s ketchup at all since i bought the pro licence, due to a lightning strike which fried the old unit. (The Gods clearly dont want me to finish this B17 project).

Now i have a new PC and thought it was time to reinstall sketchup again. But i cant get the system to recognize my serial number and or licence.? when i copy and paste the relevant info into the boxes, I get a message reading “OPPS”, the serial number begins with the wrong letter for this version.
I find all of this a bit of a dark art and dont really understand it.
Any help at this stage would be greatly appreciated. many thanks.

The license code is year specific, so if you are trying to add a 2018 license to a 2020 version it won’t work.
If you know which version the license is for then you should download that one.
I’ll ping @colin as he can often sort these issues.

many thanks. I believe i have tried this already, but to make sure, ill try uninstalling 20 and reinstall 18 now. Again many thanks.

serial no. starts with:
V - SketchUp Pro 2020
U - SketchUp Pro 2019
T - SketchUp Pro 2018
S - SketchUp Pro 2017
R - SketchUp Pro 2016
Q - SketchUp Pro 2015
P - SketchUp Pro 2014
N - SketchUp Pro 2013
M - SketchUp Pro 8
L - SketchUp Pro 7
K - SketchUp Pro 6
J - SketchUp Pro 5