You used the coarse focus rather than the fine focus

You ask Sarah to have a look at your specimen and try to focus on the slide. 

You: ‘Sarah can you please have a look?’ I think that I’m not focusing right can you please show me again how to use the coarse focus? 

Sarah: ‘I don’t see anything wrong with your technique. Perhaps the problem is something else entirely.’ 

What do you think is the problem now?