First, try resetting the app. If that does not work, then delete the app and redownload it. Finally if none of the above work, email support@athinkingape.com and report the error so they can fix it or tell you how to fix it.
now and again i get an error message, but only when i have bought several of the same packs within a short period of time. If you wait until beta wars are off then try. If still no success like stated above, try uninstall and re install the app. if that still doesn't help, email the devs