I have just started using thornit. I notice that there is a bit of the powder still in her ears days after treatment. I do not put much in, so what am I doing wrong?

Plus it does not seem to be making a difference

If the ears are wet then I use Thornit to dry the ears out and wipe with cotton wool to clear residue. Once the ear is dry I put in a pinch and leave. If you are treating a problem then you need to wipe the ears clean each day and add anopther pinch for about 5 days to make a difference. I know that it works with my dogs (and other pets) plus I've had people tell me how wonderful it is and that it has cleared a long standing infection (I'm a groomer).

Dapple

You're not doing anything wrong, this is usual. 

You might want to just wipe the ear out with a dry tissue one or two days after you've treated it.  This will give the Thornit long enough to work but also remove any residue left.

This happens with my dogs!  I just leave it in.  ATM my hand smells of a mixture of thornit and reviva coat!!!!