Maybe you have not properly reprojected the data?
You should have an entry like this in the *.hdr file after reprojecting the data.
1map info = {UTM,916.5,916.5,354930.0,6045090.0,60.0,60.0,33,North,World Geodetic System 1984,units=Meters} coordinate system string = {PROJCS["WGS 84 / UTM zone 33N", GEOGCS["WGS 84", DATUM["World Geodetic System 1984", SPHEROID["WGS 84", 6378137.0,
2298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], UNIT["degree", 0.017453292519943295], AXIS["Geodetic latitude", NORTH], AXIS["Geodetic longitude", EAST], AUTHORITY["EPSG","4326"]],
3PROJECTION["Transverse_Mercator", AUTHORITY["EPSG","9807"]], PARAMETER["central_meridian", 15.0], PARAMETER["latitude_of_origin", 0.0], PARAMETER["scale_factor", 0.9996], PARAMETER["false_easting", 500000.0], PARAMETER["false_northing", 0.0], UNIT["m", 1.0], AXIS["Easting", EAST], AXIS["Northing", NORTH], AUTHORITY["EPSG","32633"]]}