help with date refrence

See the file, You missed a comma highlighted in RED.

=IFERROR(INDEX(Sheet1!$B$1:$AE$1,,SMALL(IF(INDEX(Sheet1!$B$2:$AE$3,MATCH('PC 1'!$B$1,Sheet1!$A$2:$A$3,0),)="OFF",COLUMN(Sheet1!$B$1:$AE$1)-COLUMN(Sheet1!$B$1)+1),ROWS($A$2:A9))),"")