This error message pops up when one part of MultiCharts software is launched "as administrator" and another part is launched regular way.
is launched "as administrator" by default always. MultiCharts is not. It means that to work with TradeStation data feed, MultiCharts should be run by right-click and then the "run as administrator" option should be selected. However, if after that you run QuoteManager for instance by double click, you will get the error message.
Once a part of MultiCharts is launched with administrative rights (right-click on the icon -> run as administrator), all other MultiCharts parts should be launched the same way.
Note: If MultiCharts is launched with "as administrator" QuoteManager or PowerLanguage Editor can be launched with administrative rights too by going to File in MultiCharts main menu, then New -> ...