The setup ( although dont trust anything I say ):

I'm working on an embedded system device using a NFS mounted rootfs ( as shared by my host ) , but I store large video content directly on the device's hdd in /data.

Device's hdd partition /dev/sda3 is ext3 fs mounted at /tmp/mnt/diska3 (rw) , then I have a script create dirs like /tmp/mnt/diska3/data
and /tmp/mnt/diska3/incoming, then symlink : ln -s /tmp/mnt/diska3/data /data so that the /data appears like any other directory.

I can see /tmp/mnt/diska3/data/incoming. I did chmod -R a+w tmp to rule out permissions.

Running a subsequent script calls mkdir: mkdir -p /data/incoming/gui

BUT fails:
mkdir: cannot create directory '/data/': No such file or directory

What's the deal?

Thanks for use of your brain.. dB

minor correction:

was: then I have a script create dirs like /tmp/mnt/diska3/data
and /tmp/mnt/diska3/incoming,

should be:
then I have a script create dirs like /tmp/mnt/diska3/data
and /tmp/mnt/diska3/data/incoming,

I'm keeping this thread in General forum , see same there.