The sugar engine doesn't work

As the tooltip states, “If the tanks are already full, then this rocket can never reach that destination.”

You need to select a closer destination, one the sucrose rocket can reach. Then the message will go away.

You need an oxidizer tank with the sugar engine.

1 hour ago, Titfingers said:

You need an oxidizer tank with the sugar engine.

Thank you, I guessed this later, remembering how hydrogen rockets flew. But it is very bad that in the description of the engine there is nowhere about its oxidation, before construction.