What is this code saying ? 16: bad-txns-in-belowout (code -26)
With the Bitcoin Core Console
I get this code when I'am done signing my transaction. 
I get this message instead of a transaction ID number.
What is it ?
It means the total value of the UTXO spent by your transaction's inputs is less than the total total of the outputs.

Put otherwise, it's trying to create money.