I am a new user of the PI system, installed it last week. When I run PI SQL Commander and try to connect to my local PI server, or when I run the sample windows ADONET application I get the above error. I am able to connect to my AF Server using PI SQL Commander, but not to the PI Server. When I click to connect to the PI server in PI SQL Commander, it displays the above error message. A possibly related issue occurs when I run PI DataLink. If I search for tags on the PI Server using PI DataLink, I get an error message "Unable to connect to the PISystem", when I click OK on the PI DataLink dialog box, the results if the tag search are displayed correctly. Otherwise PI DataLink appears to run correctly. I can run the sample macro application "piexam32.xlx" which uses PutVal to write data values to PI tags.