[R] xlsx problem

[Martin Knapp]

Dear list,
I'm running windows xp with R 2.12.0. I'm trying to load a excel
spreadsheet into R using the xlsx package. I posted my code below with
the error I get.

> res <- read.xlsx("Copy of test_excel_input_data.xlsx", 6)
Error in .jcall("RJavaTools", "Ljava/lang/Object;", "invokeMethod", cl,  :
  java.lang.IllegalStateException: Cannot get a numeric value from a text cell

There are 6 sheets in that file. 5 of them are read into a dataframe
without problem. For the 6th one(the one I actually need) I get this
error message.
There is obviously something in the format of the sheet wrong. Has
anyone an idea whats going wrong and what I have to change in the
sheet?

Thanks in advance,

Christoph