Did you make the account on your computer or on the device? If on the device try logging in on the computer. If it doesn't log in on there then attempt to recreate the account. If you cannot I would suggest contacting customer service.
If you are unable to log in to either service and you can log in online you may want to delete them and go back into the market to download them again. Obviously make sure you are connected to the internet.
A generic fix that should be done is to restart the device.
Finally I would look into rooting the device and flashing the ROM so that you can try some other software for reading. Although both KOBO and Borders are nice alkido reads all formats including PDF's.
I personally don't use kobo or borders but you may need the desktop versions installed to have them link to your account.
Hope something here helps, you can follow up with some more information or troubleshooting you've done which will help the community in assisting you.