Your welcome, I was dealing with exactly the same problem and it took me some time to figure out there was that option --index missing too, see http://forum.openstreetmap.org/viewtopic.php?id=2625&p=66
So maybe it would be better when this --index would be by default turned on in the --location-autofill=bounds call?
Up to now we do not have rules in mkgmap that an option is set if another option has a specific value (I think so?!?). Do we want to have such a coupling of parameter values? I prefer to have an error message if location-autofill and/or bounds is set but index is not. I have started to change the implementation of the autofill parameters (read http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2012q3/014885.html for details). It would be good if you contribute so that the new parameter handling is more understandable than now. Thanks! WanMil