Please make sure you following the steps. 

a.  The windows admin of vSignage or Signage Manager and CDM displays or Eposters are in same LAN network . For example, first three groups of IP address are same . 192.168.1.xxx.  

b.  You can use DOS commend "ping" to reach the display's IP address and frames have no loss.

For example :

c.  The sync or save message have done and waiting for few minutes. It will depend on the campaign file size for the file transferring.  

d.  The display of the time zone and clock are setting correctly.

e. The schedule of campaign are in right time frame for playing.