Please check it according to the followings:

error tips

reasons

solutions

incorrect mnemonic

some words of mnemonic incorrect

compare "BIP39 word Library " to find the wrong word, import the correct mnemonic

length of mnemonic is incorrect

mnemonic word length is 12/18/24 words

1. Check the mnemonic word number is correct

2. separated by a space between each word

input a valid private key format. 

entered an incorrect private key

import the correct private key again