Make sure you have an ST5 code for ST5 or (guess what) an ST6 code for ST6 and that it hasn't been used before. Also note there is more than one type of Academic license.
You might be best off downloading a fresh one using your email address.
oh, i got the mistake. thank you!
Do you know where I can get a code for ST5? the code that was given to me is for ST7 i guess, but my computer can't run it...
If your machine is too old to install then it's probably too old to run it properly.
If you can't run it properly you will have a bad experience with SE and none of us wants that.
My advice is to borrow a good machine (preferably a certified workstation with a 3D CAD graphics card fitted)
Trial licenses can only be used once so if it's old it's probably already been used.
The problem is not a computer. I don't want to use another version than ST5. The problem is that the new key dosn't work. Are you sure it's demanded to download the newest version year after year and there's not a opportunity to renew a license for the installed (previous, from last year) version?