最外面的if 的 第二个参数漏了个右括号:
=IF(LEN(E4)=19,IF(LEFT(G4,10)="PrimaSleep","GIAMZ-MC",IF(LEFT(G4,4)="Olee","GLAMZ-MC",IF(LEFT(G4,9)="SLEEPLACE","SKAMZ-MC",IF(LEFT(G4,4)="Ecos","ECAMZ-MC","Warning")))),IF(AND(LEN(E4)<=5,LEN(E4)>0),"GLEBY-MC",IF(LEN(E4)=9,IF(LEFT(G4,11)="Sleeplanner","GLOSK-MC","GLNEG-MC"),"Warning")))
前面应该是ifs。望采纳