Possible error with sharperatioLines() from fPortfolio

I believe there might be an error with the function sharperatioLines() of fPortfolio package. When using sharperatioLines() to plot the curve of the Sharpe Ratio it also plots a light blue circle, which should be its maximum point. That point should also be the point where the Capital Market Line tangencies the Efficient Frontier, which can be plot using tangencyPoints(). However, the two points are not matching. Does someone have an idea of what is happening? Here is an example:

library(fPortfolio)

#simulates two assets' returns
set.seed(1000) 
ab2 <- assetsSim(1500, method="sn",
                 model=list(beta=c(0.000555,0.000724),
                            Omega=matrix(c(2.772225e-06,-0.9*0.001665*0.002172,
                                           -0.9*0.001665*0.002172,4.717584e-06),2,2),
                            alpha=c(0,0), nu=0))

#transform to time series
ab2 <- as.timeSeries(ab2)

#calculates portfolio frontier
port_ab2 <- portfolioFrontier(ab2)

#plots the frontier
frontierPlot(port_ab2)#, xlim=c(0.0005,0.0025), ylim=c(0.0005,0.0008))

#adds the sharpe ratio line
sharpeRatioLines(port_ab2, col="orange")

#adds the capital market line
tangencyLines(port_ab2, col="green")

#adds the optimum portfolio
tangencyPoints(port_ab2, col="green", pch=19)