Link2sd Sony C3 Dual

hallo guys

it's my first time here.
:angel::angel::angel:
I have two phones Sony Xperia C3 dual:

Lollipop 5.1.1
Rooted with Kingroot
Stock ROM

for both of them.

I rooted the first one and uninstalled some system Apps and linked all Applications to SD card second partition (EXT2) with Link2sd application.
and everything is working very good with no problem.

NOW MY PROBLEM IS WITH THE SECOND PHONE:

1- I couldn't link my apps to the second partition, The link2sd app couldn't mount the script
It says to me:
"mount script cannot be created cannot unmount /data/sdext2: invalid argument mount: Operation not permitted"

I tried all (EXT2,EXT3, EXT4, FAT32)

2- I couldn't uninstall some System Apps
I tried with:
Titanium backup
Link2sd
Kingroot
all of them just hide these Apps and when i restart my phone they appear again.

3- I couldn't use the ADAWAY App to block the ADS.

4- I'm not sure if i will have other problems later with it

So i'm very confused about these phone what's the wrong with them


finally i wish i could explain everything in a good way, and you can help me

thanks