Sometimes when the Ultra VNC is used for the connection to the slave measurement units the error appears:

In such a case, follow these steps which will help you resolve the problem.

1. Make sure that Ultra VNC server is running on the unit which you are connecting to.

This can be checked in the bottom right corner of the screen. There should be a blue icon like shown on the picture below:

2. Check if the VNC password is set up correctly. 

By default the password in Dewesoft is set to "a", but it can be also changed in Dewesoft options (Options -> Settings -> Advanced -> NET -> Setup screen connection -> Default password)

If you are using the default password, set the VNC password to "a", and if not, set it the same as in Dewesoft:

3. If the issue is still not resolved, the problem is that the installer didn't correctly register two dlls. Those dlls are "VNCX.dll" and "scvnctrl64.dll" (they are available here as an attachment). To register them you need to open the command prompt in the admin mode ("Run as administrator") and use the command regsvr32 (example: "regsvr32 VNCX.dll") to register the dlls. In case you are using 32-bit Dewesoft you only need to register "VNCX.dll" or in case you are using the 64-bit version you need to register "scvnctrl64.dll". After you register both dlls the VNC should work.