Error when running optical_input (siesta 5.0.0)

Dear siesta user,

after a successfull generation of *.EPIMG and e2.dat files, I am trying to run optical_input utility to compute the real part of the dielectric function. However, I encounter the following error :

0 0.000000000000000E+000 0.000000000000000E+000
forrtl: severe (64): input conversion error, unit 5, file /proc/3784857/fd/0
Image PC Routine Line Source
optical_input 00000000004116DB Unknown Unknown Unknown
optical_input 000000000042D4A0 Unknown Unknown Unknown
optical_input 000000000040E218 MAIN__ 36 optical_input.f
optical_input 00000000004037E2 Unknown Unknown Unknown
libc.so.6 00007F19A7E01D90 Unknown Unknown Unknown
libc.so.6 00007F19A7E01E40 __libc_start_main Unknown Unknown
optical_input 00000000004036EE Unknown Unknown Unknown

Any thoughts?