Installing superuser on Android Debug Build (no su binaries)

I am currently doing lab work on an upcoming device and I hit the wall on this particular one.

I can't tell the model number, but it is running Android 5.1 and the build is LMY47D

This is a user debug build - so I have the SU binary and busybox installed, and I am perfectly able to run all and all su commands.

I have a SU binary located at "system / bin /" and it is linked to "/ system / xbin /." It has root access and the correct privileges (I think). Also you can see that the boot box is installed.

If I have a problem installing superuser and several other applications.

I installed applications in the "system / app /" folder with 755 privileges along with appdel.apk and appdel2.apk (the ones I need to give root access too)

Here is a snapshot of the "/ System / app" folder.

As you can see, everything is there with root privileges, but when I try to access the application, nothing works.

How can I provide these apps with Root Access?

As a side note, I cannot flash or reload this ROM. Queen Root and IRoot just lured the phone. The superuser I'm trying to install is 2.46, which is the same superuser that the guys at Nexus Root use on their LMY47D devices.

This is one of the tutorials I follow (among others): http://pocketnow.com/2012/10/10/root-without-unlocking

Thanks guys,