[TYPO3] Using SinglePid from Categories

[Amir M.]

Hi,

I am having trouble using this.  Can someone explain to me how exactly I 
can enable this correctly with all the conditions?  The only condition 
it says in the category page when specifying the singlepad is to insert 
the following line into my TS Constants, and I have already.  Yet, it 
seems to have no effect:

useSPidFromCategory = 1

Thanks,
Amir.