IBrokers twsFOP calls R

I am trying to get the following to pull some data from IB (Nasdaq 100 e-mini futures options data). I am using snapShot callback (see below). Can anyone tell me what is wrong with my code?

require(IBrokers)
tws <- twsConnect()
test3<- twsFOP("NQ","GLOBEX",expiry="20141121",strike="4000",right="C")
test4 <- reqMktData(tws, test3, eventWrapper=eWrapper.data(length(1)),CALLBACK=snapShot)

      

        
        
        
      

    

Thanks a bunch. I searched high and low online and found little documentation on twsFOP apart from CRAN documentation which points to twsFuture. The snapshot call is given below:

snapShot <- function (twsCon, eWrapper, timestamp, file, playback = 1, ...)
{
  if (missing(eWrapper))
    eWrapper <- eWrapper()
  names(eWrapper$.Data$data) <- eWrapper$.Data$symbols
  con <- twsCon[[1]]
  if (inherits(twsCon, "twsPlayback")) {
    sys.time <- NULL
    while (TRUE) {
      if (!is.null(timestamp)) {
        last.time <- sys.time
        sys.time <- as.POSIXct(strptime(paste(readBin(con,
                                                      character(), 2), collapse = " "), timestamp))
        if (!is.null(last.time)) {
          Sys.sleep((sys.time - last.time) * playback)
        }
        curMsg <- .Internal(readBin(con, "character",
                                    1L, NA_integer_, TRUE, FALSE))
        if (length(curMsg) < 1)
          next
        processMsg(curMsg, con, eWrapper, format(sys.time,
                                                 timestamp), file, ...)
      }
      else {
        curMsg <- readBin(con, character(), 1)
        if (length(curMsg) < 1)
          next
        processMsg(curMsg, con, eWrapper, timestamp,
                   file, ...)
        if (curMsg == .twsIncomingMSG$REAL_TIME_BARS)
          Sys.sleep(5 * playback)
      }
    }
  }
  else {
    while (TRUE) {
      socketSelect(list(con), FALSE, NULL)
      curMsg <- .Internal(readBin(con, "character", 1L,
                                  NA_integer_, TRUE, FALSE))
      if (!is.null(timestamp)) {
        processMsg(curMsg, con, eWrapper, format(Sys.time(),
                                                 timestamp), file, ...)
      }
      else {
        processMsg(curMsg, con, eWrapper, timestamp,
                   file, ...)
      }
      if (!any(sapply(eWrapper$.Data$data, is.na)))
        return(do.call(rbind, lapply(eWrapper$.Data$data,
                                     as.data.frame)))
    }
  }
}