udev not running rule at boot?

I have a very simple udev rule at /etc/udev/rules.d/sdcard.rules:

KERNEL=="mmcblk1", SUBSYSTEM=="block", SYMLINK+="sdCARD"

Problem is the symlink is not created for me automatically at boot. I have many other rules and all them work just fine at boot (my symlinks are created).

However, if I run this then the symlink IS created:

udevadm test /block/mmcblk1

What could be going on here? Why isn't it created at boot? Could the device not be available yet? How could I find that out?