You probably have the following options:

1. Check with Soti technical support or business support  for any updated Android+ agent for EA600 if you are or are going to  a licensed customer.

2. Use the generic Android agent .  This should always work, but some advanced features available only in Android+ will not be supported.  (Depending on you server versin, you might need to contact Soti support team to ask how you can have the hidden Generic Android platform re-enabled)

3. Check if Unitech will release any firmware upgrade (hopefully Android 6.0+)  to make it a Android Enterprise compatible device.  If so, you can then use MobiiControl Android-Enterprise agent. (According to a web page on Android Enterprise maintained by Google, Unitech is currently not on the list.    However, the list may be outdated and/or incomplete.   You can always check it out in a few minutes simply by factory resetting the device and input afw#mobicontrol when prompted for your Google account). 

What version of the server did you use?  Is the server a production server with different brand/model of devices of different platforms enrolled?

What did you see on your web-console and on your device  screen for each case  (especially for UNITECH EA600 agent v13.3.2) ?  

The mobicontrol server is in version 14.1.2.1937

Actually there is no brand/model of devices enrolled on server.

I have this message on the device after install and launch agent:

"this terminal agent is incompatible with your temrinal. please contact your administrator"

I see nothing on web-consol

Thanks