She is fine if I catch her just in time and plonk her on. And she does her wees on either with no fuss and only the occasional accident now.
But poos, nope.
We did potty training back in Oct/Nov (can't actually remember) so surely this should have resolved itself by now?
Her twin is managing fine so it can't be a simple case of me having done it all wrong 
What can I do?