[Q] Adding Apps to Settings Apktool / Smali topic

Hi there, i'm trying to add the xposed apk to the settings menu. I've decompiled the apk, modified the lines of code required, deoxed it (smali / baksmali) and recompiled the apk. Ive pused the settings file back, changed the relevant read write permissions. It shows fine in its directory. Restart phone and settings wont open... Ive got the original settings apk & odex files and as soon as ive pushed those back settings works. Ive tried signing the modified apk, but im just clutching at straws at this point.

Can anyone advice? Has anyone done the same successfully? Appreciated