I suspect there is a bug in your help file. The topic about TIELayer.LayerIndex has this sample code:
// Move the current layer to pos 1 (first layer after the background layer
ImageEnView1.LayersCurrent.LayerIndex := 1;
I found that ImageEnView1.CurrentLayer.LayerIndex is the correct code.
The CurrentLayer help topic includes this, which appears to be incorrect:
Note: Use LayersCurrent to get or set the current layer index. Use CurrentLayer to return the layer object.
J.R.