// previous
isTime = time(timeframe.period, i_Time + ":1234567")
bgcolor(i_BkGr and isTime ? color.new(color.gray, 50) : na)
// revised
isTime = not na(time(timeframe.period, i_Time + ":1234567"))
bgcolor(i_BkGr and isTime ? color.new(color.gray, 50) : na)