why is a Lie algebra not nilpotent even if an ideal is nilpotent and algebra quotient by ideal is nilpotent

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Why can't we use the same arguments as for solvability to say that If a Lie algebra $L$ has a nilpotent ideal $I$, and $L/I$ is nilpotent, then $L$ is nilpotent. Can someone point out the fallacy in the argument