I'm trying to place a Cover order but it's being rejected & an error "syom:Co:auto square off executed" is shown. Why is this?

syom:Co:auto square off executed

If a Cover Order is placed after an existing CO position has been auto squared off [i.e by RMS at the cut off time - 3:20pm for EQ & FNO, 11:05pm for MCX] the order will be rejected and this error will be displayed,