It's not the field name you should be using. I've already mentioned this.
If you right-click that image control > click Properties in the pop-up menu > click the Other tab, you will find the Name of the image control.
So to re-iterate, you want the name of the control that houses the field.
If you right-click that image control > click Properties in the pop-up menu > click the Other tab, you will find the Name of the image control.
So to re-iterate, you want the name of the control that houses the field.