Please help me.

I followed all the processes, but after I have my signed transaction text which has to be pasted in the fee booster script, it shows: "Transaction being broadcast. TXID: null". No fee boost happened.

Is it something to do with my Electrum wallet?
I have pasted the modified unsigned transaction text into the sign/verify message window in there, with my current wallet address. It generates the signature (maybe incorrectly ) and then it doesn't work in the script after I paste it and want to send the transaction. It shows that TXID: null message.

Thanks for your help in advance.