hi,
Couldn't change the subject line to add solved...
Indeed I needed to ground the V- and I tried that but still no luck. Then I decided to rewire the thing step by step on another breadboard using only 3 LDRs and that worked. I verified if the new version was wired similarly to the troubled one and it was. So I suspect a (cheapo chinese) faulty breadboard. Then I added the array of 13 LDRs and it still works on the new one so this one is solved.
Thanks!
Jhh