I/O Simulator in Auto mode

When I try to simulate inputs in Auto mode I get the message: 'Failed to set value for signal ....., check access rights.' The I/O simulator works OK in Manual mode.

I need to test some logic which responds differently to inputs depending on whether the controller is in Auto or Manual mode.

Where must I look to check access rights, and how can I grant the I/O simulator access rights in Auto mode?

Thanks for any advice,

Kevin.