Trailing stop order of IBrokers in R

Question

Here is a condition that I want place a TRAIL order with stop price is 43.41 and trailing Percent is 2%.

I use IBrokers.zip of joshuaulrich from github.

However, when I place TRAIL order with trailing Percent, the order is not contained with trailing Percent.

Here is my code,

twsOrder(action = "SELL", totalQuantity = 399, orderType = "TRAIL",trailingPercent = "2", tif = "GTC", transmit = FALSE, trailStopPrice = 43.41)

the picture that i want to place order on IB

What am I missing? And how can I solve the problem?