Reprojecting a raster image using gdalwarp

I am trying to reproject an ECW Orthophoto from 25830 to 23030 srid.
I tried the following but I am getting an error:

C:Program Files (x86)FWTools2.4.7>gdalwarp -s_srs 25830 -t_srs 23030 C:orto.e
cw C:orto_ed50.ecw
ERROR 1: Translating source or target SRS failed:
25830