[R] Problem with plm package

[george brida]

Dear friends,
I have a csv data entitled GFS in the following path:
c:\TEG
This data is attached with this mail.
When I wrote the following lines:

y=read.csv("c:\\TEG\\GFS.csv", header=FALSE, sep=";")
  purtest(y, pmax = 4, exo = "intercept", test = "hadri")

I obtained the following message:

Error in Math.factor(x) : cumsum not meaningful for factors
In addition: There were 50 or more warnings (use warnings() to see the
first 50)

where's the problem? can you please help me
Thank you in advance
George