When i copy executable file on SD card it missed or 0 length

I compile *.c file using arm-gcc 4.3.2 with toolchain code blocks on my
ubuntu host.
after that plug sd card and copy onto it, remove it and attach to my 2440
target board, start linux and when i go to /sdcard directory it was missed
or its there but with 0 length !
Please help !

$ man umount

Thank you! 
So pitty, but i lost 2 hours :-)