Do you have already tried ALL adb drivers ? Are you sure about it ? Try to uninstall the adb driver with the software below (x86 or x64 ... it depends from your Windows OS) :
[Only registered and activated users can see links Click here to register]
And then, try to install the drivers below :
[Only registered and activated users can see links Click here to register]
Please READ CAREFULLY the next steps :
Remember to disable Driver Signature Enforcement on Windows 8.
1) Press the Win + C keyboard combination to bring up the Charms Bar, then click on the Settings Charm.
2) We need to head into the Modern Control Panel, so go ahead and click on the Change PC settings link.
3) When the Control Panel opens, switch over to the “Update & recovery” section.
4) Then click on the Recovery option on the left hand side.
5) Once selected, you will see an advanced startup section appear on the right hand side. You will need to click on the “Restart now” button.
6) Once your Computer has rebooted you will need to choose the Troubleshoot option.
7) Then head into Advanced options.
8) Then Startup Settings.
9) Since we are modifying boot time configuration settings, you will need to restart your Computer one last time.
10) You will be given a list of startup settings that you can change (press the F7 key).
OTHER STEPS :
Right click and select Update Device Driver Software.
Select Browse my computer for driver software.
Select Let me pick from a list of drivers installed on my computer.
Select Show all and click next.
Click Have Disk, then Browse.
Go to your extracted folder and go into it, until a file called (android_winusb.inf ... for example) is there. Double click that.
Click OK and then Next (If it says not signed, just click next anyway).
Wait and if it says not signed, click install drivers anyway.