keydefs based on product attribute

I am trying to assign different values to one key name and differentiate them based on the product attribute such that when I refer to them using the keyref command they take the corresponding value for their product. But it apparently ignores the product and all the keywords for all the products take the value of the first keydef. Here is an example for three different products

<map>

<keydef keys="program" product="measurement_program"><topicmeta><keywords><keyword>measurement</keyword></keywords></topicmeta></keydef>

<keydef keys="program" product="evaluation_program"><topicmeta><keywords><keyword>evaluation</keyword></keywords></topicmeta></keydef>

<keydef keys="program" product="backup_program"><topicmeta><keywords><keyword>backup</keyword></keywords></topicmeta></keydef>

</map>

Then, I assign the corresponding product attribute to the element where I use the keyword. I would expect that the value of the keyword changes within the bookmap according to its product but this is not what happens. In my example all keywords show "measurement"