@salahkhani, are you using gprs connection when trying to send original photos taken by N900?
I tried sending original photo from N900 camera when I was connected to gprs once, but it failed.
I suspect it was because the photo was several hundred KBs and gprs connection not reliable enough for sending it.
Anyway, you should resize your photos before send it on whatsapp, because I don't think your friend will be happy if you always send pictures > 100KB.