Need help rooting Acer Iconia tab 8 a1-840FHD

I have an Acer Iconia Tab 8 A1-840FHD

Android version 4.4.2
IAFW version 0007.0052
Kernel version 3.10.20+
Image version Acer_AV0K1_A1-840FHD_RV0WRC01_WW_GEN1
Build number Acer_AV0K1_A1-840FHD_1.062.00_WW_GEN1
Image P/N FM.NNRA0.01D

When I follow the guide on the forums here: http://forum.xda-developers.com/andr...40fhd-t2933317

I get the following error message:

DEVICE STATUS: ADB-ONLINE

DEVICE INFORMATION: adb server

=======================================

adb server is out of date. killing...
ADB server didn't ACK
" failed to start daemon "
error: unknown host service
< waiting for device >


What am I doing wrong?