Transfer Stx from old stacks wallet to Hiro

I had forgotten about the tokens purchased during the ICO and in my original STACKS WALLET until recently.

I have tried but am unable to transfer them to the HIRO wallet. I added the amount of BTC required to the old wallet, but then the amount changed so I added more BTC. However, now when i attempt to send nothing happens. I tried suggestions made in the chat thread to use the HIRO wallet and my old recovery phrase but it won’t accept my 12 word phrase. It wants a 24 word phrase instead (which I don’t have).

How can i gain access to my tokens? Please advise. Thank you.