Spindle Speed display backwards

I'm trying to configure a lathe using Linuxcnc 2.9. Now I'm adding an encoder like the one in the attachments. I used the stepper config wizard, selected custom pyVCP GUI panel and the spindle speed display option. I tested the encoder using Hal Meter and the connection is fine. When I turn the spindle on the speed display starts to count, but with wrong values and when I increase the speed this value decrease until reach 0.
I tried some troubleshootings in hal files, but I'm really newbie in Linuxcnc.
I'm using a BOB like the one in attachments.
My VFD is the 9600 nflixin
Here is a  video  about the problem
 

My encoder is the LPD3806-360BM-G5-24C with 360 PPR.
It's connected with a 1:2 reduction so I'm putting 720 cycles per revolution in Linuxcnc, is this right? 

You are right, Tommy it's a paraport limitation.
I tested using an optical sensor, like the one in attachments, and a disk with 4 roles and it worked.
Strange because in this  video  the guy uses an encoder with 200ppr and a reduction of 1:2 resulting in 400ppr. I think that worked in video because he's using linuxcnc 2.7.14 with a better latency than mine.
 

I'm already running the RTAI kernel and my latency is 35k. I only get a good latency with 2.7.14, but in this version the G71 doesn't work.
I watched this  video , the guy is runnig 2.7.0 and using the G71 but I have no clue how he managed that.