May be it is already connected to a demand plan server. 

You can go to the demand plan server window and populate. Then you can select each demand plan server and check the connected host and find out what demand plan server ID is connected to the demand plan server running in the host.

/Sangeetha Jayamaha

@Alain de Martin de Viviés 

As per the screenshot, the demand plan server ID 1000 is already connected to the demand plan sever running in the Host psd1-s1-d01-ao . Please elaborate more on the issue that you are having.

/Sangeetha Jayamaha

@Alain de Martin de Viviés  Since we restarted the demand server now this issue also should be solved.

Can you verify? 

From the post: https://community.ifs.com/manufacturing-supply-chain-procurement-142/demand-server-down-7543?postid=36015#post36015  the demand server was restarted.

/Sangeetha

I works, thanks a lot

Alain