Hi,

It can be two things:

- Operator does not have the correct authorization

- OS_Perm bit is disabled

Please check the block in CFC and under properties, to go the Start I/O and check which OS level is assigned. It can be a number like 1,2,3. Default it set at 1 so the operator with: Process Controlling can press the button. Level 2 is Higer Process Controlling and 3 is Highest Process Controlling

If this is not the case, the OS_Perm bit can be disabled (set at 0) so the user in WinCC is not allowed to use the Start command.