R1C1 If Formula - Keep getting Error

This is the formula I'm using

Range("J2").Select ActiveCell.FormulaR1C1 = "=IF(RC[-8]="","",=R[-1]C+RC[-4]+RC[-3]+RC[-2]"

I keep getting the following error

• Run-time error '1004': Application-defined or object-defined error

The goal is to look at RC[-8]. If it's blank, then leave active cell blank. If it's not, then take the cell above and add it to RC[-4]+RC[-3]+RC[-2].

Please help!