KOBO download to ADE 3.0 problems ?

I am unable to download kobo books to ADE03.0 I was using ADE 4.5 ok until I tried to download from KOBO. KOBO told me I needed ADE 3.0. I downloaded ADE 3.0 but that doesn't work either. I uninstalled ADE 4.5.  ADE 3.0 tells me that my computer is authorised. However  I still cannot transfer kobo files. ADE 3.0 refers to an activation problem. Can anyone help?