> data=read.table("/home/qiime/Desktop/R_correlation/R.txt",sep="\t",header=T,row.names=1,comment.char = "" )
>  data=na.omit(data)
>  library(PerformanceAnalytics)
> chart.Correlation(data,histogram = TRUE,pch=19)
There were 50 or more warnings (use warnings() to see the first 50)
> warnings()
Warning messages:
1: In plot.window(...) : "method" is not a graphical parameter
2: In plot.xy(xy, type, ...) : "method" is not a graphical parameter
3: In title(...) : "method" is not a graphical parameter
4: In plot.window(...) : "method" is not a graphical parameter
5: In plot.xy(xy, type, ...) : "method" is not a graphical parameter
6: In title(...) : "method" is not a graphical parameter
7: In axis(side = side, at = at, labels = labels, ...) :
  "method" is not a graphical parameter

保存为PDF时看不了图片怎么办？求大神指点