problem using pkg install : "Package is missing file: COPYING"

hello, I want to install the netcdf package for octave (with octave 2.9.9 on an intel mac). Here is what I get : octave:2> pkg install /Users/timbrochier/Desktop/Telechargements/ octave-intel-bin.tar error: Package is missing file: COPYING octave:2> If anyone can help me fixing that, o tell me another way to install the package... Thank you very much, Timothee