Whenever you keep getting "Trade is not allowed in expert properties" when using VTC, please make sure that you've enabled "Allow automated trading" in Expert Advisors options as shown below:
Additionally please make sure that the automated trading switch is enabled:
— automated trading enabled, trading functions in launched applications are allowed for use.
— automated trading disabled, running applications are unable to execute trading functions.
Sometimes the above is not sufficient. In that case please remove MT4io from your chart and re-attach it making sure the "Allow live trading" is checked (as shown below):
Please remember to restart VTC and MT4 after you make the changes.