You missed a very crucial element of lsat. It seems as though you are a lsat beginner so don't worry you will catch up soon.

Basically All indicates sufficient

Only constitutes necessary.

THE ONLY constitutes sufficient.

All red objects are trucks

RO ---> T

/T ----> \RO

Only the good die young

DY ----> G

\G ----> /DY

The only fun game is logic game

FG ----> LG

/LG ----> /FG

I would highly recommend you review your sufficient and necessary language indicators.