Quote from: Kulahin on April 01, 2018, 07:46:42 PM

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Invalid mnemonic

two of my seeds have 11 words.

According to the BIP 39 standard, seeds need to be a fixed length of entropy: 128, 160, 192, 224 or 256 bits. That's 12, 15, 18, 21 & 24 words respectively.
So either your seed phrase isn't complete, or it isn't a BIP 39 seed at all.
Your seed needs to be at least 12 words.

"Invalid mnemonic" means that either the words are incomplete, are in the wrong order (the order matters, the last word is a checksum), or one or more of the words isn't in the BIP 39 word list.

You still haven't said what wallet created the seed phrase.