ADE - authorizing device

Hi, I was using ADE with my kobo e-reader quite happily but decided I wanted to sync books onto my mobile phone. After many attempts found out I couldn't do it anyway (I read library books and you can only have them on one device). But now I'm not given the option to do anything with the device authorization on my kobo - it's all greyed out. So now I can't re-authorize it. I think ADE "thinks" I have authorized too many devices.but I haven't - only my computer. Any way round this please?