Ha ! Good catch ! And it would explain quite elegantly why it didn't work for me.
Also, what I failed to mention to you when I made my initial post is that, I, too, was fearing for my sanity and though that maybe it had something to do with the map not being developped by ED. So I went into Caucasus and tried the same procedure with various oil tanks scatered around the map and got the same non-result. So it does seem to be the case on at least these two maps.
Now, does that mean that if I wanted to count the oil derricks as valid target and have them allow points as well, I shoul put their name in full caps in the Score Table ? Are all the scenary objects typeDesc upper case ? If I wanted to check that on my own and not bother you where would I be able to check it ?