She has never weed or pooed on the potty or in the toilet.
I have kept her nappy off all day today (this is about the fourth attempt). she had four accidents, all of which distressed her. The last one considerably so. She was crying and saying 'I don't like it when I wee' 
She does not seem to have any warning/recognise when she needs to wee. I sat her on the toilet and potty at regular intervals during the day, but nothing happened.
What should I do next? Keep going or stop and try again in a while?