Any Idea to prevent the warning message? library(XLConnect) wb <- loadWorkbook("writeWorksheet.xlsx", create = TRUE) createSheet(wb, name = "CO2") writeWorksheet(wb, CO2, sheet = "CO2",rownames=c("",1:84)) saveWorkbook(wb) Warning message: In names(res)[1] <- colname : number of items to replace is not a multiple of replacement length