If you have followed the procedure correctly then there is a problem between MultiBitHD seed and ElectronCash wallet.What you should do is to download Electrum Bitcoin wallet and try to use seed from MultiBitHD to get your BTC in Electrum Bitcoin wallet.Then use seed from Electrum to claim BCH(I do not know why you use ticker BBC).

For safety measures you should not use that Electrum seed to claim BCH until you send your BTC to new address.There is full guide how to do it on safe way,just check in Electrum topics.