[Q] MTK Droid Tools error

I have an MTK6575 based device.
I made a CWM recovery for it with MTK Droid Tools and flashed it.
Then I rooted it with MTK Droid Tools.
Everything was working fine.

Then I made a backup with MTK Droid Tools.
I restored the backup from CWM.
SuperSU works fine and grants permission to Root Explorer which also works fine.
But 'getprop: permission denied' is shown in front of most of the headings in 'Phone information' tab in MTK Droid Tools.
And when I click 'Root' button in MTK Droid Tools the following message is shown 'ERROR: SU inaccessible'.
I have granted permission to ADB Shell in SuperSU.
If I manually open adb shell I get $ prompt and then I type su to get # prompt.
I think that maybe permissions of some files are not ok.
Please help!