Error message E_AUTH_BAD_DEVICE_KEY_OR_PKCS12, can't erase authorisation, can't find activation.dat

When I try to download a new book it comes up with the error message E_AUTH_BAD_DEVICE_KEY_OR_PKCS12. I read that to fix this you need to erase authorisation, so I tried to do that but it says 'unable to erase authorisation. please try after some time'. It's been saying that for a few months. Then I read you can manually delete the activation.dat file to erase authorisation, but there is no authorisation.dat file (nor Digital Editions folder) on my laptop. What should I do next? Thanks