[R] Prompt comes too late

[Ralf Finne]

Hi R fans

I am trying to make a program to ask the user to choose data file:

print("Choose data file please !")

matr=read.table(file.choose(),dec=".",header=TRUE)

The problem is that the prompt 
Choose data file please !   
comes after I have chosen the file.

What  am doing wrong?

Thanks in advance
Ralf Finne