Journals not allowing 'narrations' to be entered

When entering Journals (to record cash income and expenses) Reckon throws a hissy fit each time I try to type in a narration. First of all it comes up with an error message 'The account name already exists and is currently not valid for this type of transaction, please select a valid account. Do you want to add a new account instead?' 
Then if I close the error box and enter the narration, the whole thing jams up and I can't save or add new lines without deleting the line. 
After much playing around with it I have now worked out that it works & allows me to enter a narration ONLY if I enter each line in the following order: Select account, then select the tax code, then enter the narration, then enter the amount. The problem seems to be isolated to Purchases transactions not Sales.
PS. I am an accountant and am well aware that my chart is set up correctly and that this error should not be occurring. This is yet another frustrating glitch with Reckon One.