Hi,
Do you have the same issue when you load the data by using a read function?
library("xlsx")
myFile = read.xlsx("myExcelFile.xlsx", sheetIndex = 1, header = TRUE)
In the above example, the read.xlsx takes an Excel file, then the sheet in the excel you like to read (usually 1, but could be you have data in other sheet) and a specification whether the first row is the column names (header = TRUE or FALSE).
Let me know if this also generates the error...
PJ