Incorrect number of event procedure arguments
An event procedure for a control array needs to be defined with the Index argumentfor example, Command1_Click (Index as Integer), while an event procedure for a non-control array cannot take the Index argument. Check the control's Index property. If it is non-null then the control is considered part of a control array.
An event procedure was written for a control before the control was made part of a control array or before the control was removed from a control array. In either case, the number of arguments is incorrect, either because the index needs to be added or because it must be removed. Edit the event procedure in the Code window to add or remove the index argument.
An argument has been added or removed from the event procedure definition. You can determine the correct syntax of the event procedure by looking at Help on the event.