Default help please

hi
apktool works 100% with any apk i use it with only the following.

Pocket AMC Reader_1.9.1.apk

when i decompile and rebuild and sign the apk wont work at all. (even if i dont make any changes to it)

any help would be great.

i have included this apk as an attachment to see if anyone can help.
Attached Files
File Type: apk Pocket AMC Reader_1.9.1.apk - [Click for QR Code] (558.2 KB, 1 views)