Fortran runtime error: end of file

Hello everyone,

I have a strange problem. Consider the following fortran program:

program test
    real :: arg

    open(unit=1,file='test.txt',status='unknown')
    read(1,*) arg
    print *, arg
    close(1)
endprogram

test.txt simply is one line with a floating point number -- such as 50e-9.
If I compile and run the code on its own, everything is fine:

$ f95 -g -o test test.f90
$ ./test
   5.00000006E-08


However, if I run the program within DDD, I get

At line 5 of file test.f90 (unit = 1, file = 'test.txt')
Fortran runtime error: End of file
[Inferior 1 (process 16664) exited with code 02]


Does anyone know why the program works fine when run outside DDD but gives
an error when run inside DDD?

Thanks for your time.
-Leon