Let all apps read my external SD card
Sometimes CyanogenMOD messes with the SD card paths after rooting. If that is the case, you will need to use a terminal emulator to correct the path to /sdcard/external_sd

Make the external_sd folder in your SD card first. Then through the emulator use the command

su

mount -o bind your_current_path_as_per_es_explorer /sdcard/external_sd