Correct email deemed incorrect in apps

[LAhanger]

I have KOBO's e-reader on my EVO, and it says my email address is not valid. I checked the web version on my computer, and it lets me log in no problem. This has happened in other apps before, where I use a valid email, or date, and it tells me that it's not valid. Is there a known fix for this? I've tried uninstalling and re-installing the app, all to no avail. TIA