Error whit "platforms add"

i have this error EISDIR
i dont undertand

C:\xampp\htdocs\hello>cordova platforms add android
Creating android project…
Error: EISDIR, illegal operation on a directory
at Object.fs.readSync (fs.js:476:19)
at Object.fs.readSync (C:\Users\ususario\AppData\Roaming\npm\node_modules\co
rdova\node_modules\tar\node_modules\fstream\node_modules\graceful-fs\polyfills.j
s:218:23)
at Object.fs.readFileSync (fs.js:315:28)
at C:\Users\ususario\AppData\Roaming\npm\node_modules\cordova\src\platform.j
s:283:42
at _fulfilled (C:\Users\ususario\AppData\Roaming\npm\node_modules\cordova\no
de_modules\q\q.js:798:54)
at self.promiseDispatch.done (C:\Users\ususario\AppData\Roaming\npm\node_mod
ules\cordova\node_modules\q\q.js:827:30)
at Promise.promise.promiseDispatch (C:\Users\ususario\AppData\Roaming\npm\no
de_modules\cordova\node_modules\q\q.js:760:13)
at C:\Users\ususario\AppData\Roaming\npm\node_modules\cordova\node_modules\q
\q.js:821:14
at flush (C:\Users\ususario\AppData\Roaming\npm\node_modules\cordova\node_mo
dules\q\q.js:108:17)
at process._tickCallback (node.js:415:13)

I think it is just cordova platform add android without the “s”.

I have the same problem with this above (even with the right command)