spotAngle won't set Cookie Size on Directional Light?

Hi According to the scripting reference, using the spotAngle parameter should set the cookie size on directional lights, but it doesn't seem to work. Setting the spotAngle within a script has no effect on the light and in fact

print(dirLight.spotAngle);

always shows 1, even if the cookie size is set differently in the inspector.

Is there a workaround to set the cookie size programmatically?

Thanks

Directional lights don't use the spot angle parameter, that's only for spotlights. Use cookie size!