OMG Tammy & Flowerchild, thankyou SOOOO much for bringing this discrepancy up. I have only ever used OPK's from ebay and have never got a + result, not even a faint -ve. I was starting to think that I wasn't Oing or there was something wrong (despite having other signs of O). I will now switch to another type of OPK as the cheap ones obviously don't detect my LH surge.
Thanks so much for putting my mind at ease!! =D>