[Q] Root Iconia B1-750 topic

Hi,

I'm trying to root my Iconia B1-750 but still not able to do it.

I tried :
the solution in this tread http://forum.xda-developers.com/andr...p-cwm-t2975096

but got this error when the tablet reboot :

E:installer device ignored
FASTBOOT INIT ...
E:Failed to mount device '/dev/block/sda1' as installer partition using fs_type 'vfat'
E:installer device ignored
E:installer device ignored
E:No valid installer medium found.
FASTBOOT CMD WAITING...
Could not open /sys/devices/virtual/blacklight


Anyone retrieve a solution ? please help
Is it a problem of bootloader locked ?

Thanks

xda-developers