Click on the box to choose whether the sentence is correct (C), contains a comma splice (CS), or is a fused sentence
(FS)
Don't stack twelve boxes on top of one another, it's the twelfth one that will knock down the pile.
"Don't stack twelve boxes on top of one another" and "it's the twelfth one that will knock down the pile" are independent clauses and should be linked by a colon, semicolon, or conjunction.