"The purse of Gabriella is bigger than that of Mary" should be accepted.

When i had to translate this sentence from English to Romanian, the answer had ca cea a mariei. Now that it is the other way round, the cea has disapppeared. Does anyone know a reason for this? Or are both versions acceptable or is this a bug? (excuse my english - shouldn't be starting sentences with a conjuction sorry!)

'Gabriella's purse'