Problems with collections on Kobo Aura

Hello all
I have been using Calibre for quite some time to transfer epubs to my Kobo Aura.
Up till now, I have added the books into Calibre, edited the metadata to set Author and Series and sent to the Kobo.
eg. if I have a set of books author F Bloggs, and I decide I want them to be stored in a series TheseBooks then I set these in Calibre and send to the kobo. The books have always been stored under a folder with the author name, and are accessible through a collection of the series name.
Recently I have had to replace my pc due to sudden and catastrophic death of my old one. I installed Calibre and the Kobo software, but now when I send to device, the books are stored under author as before, but the collection does not exist.
Can anyone advise me?