Opk and urine color?

I have been using opks and I was wondering if the color of your urine influences the tests. The two days I got positive opks my urine was a dark yellow and the days that I didn't get positive were yellow but a paler yellow. I've still been having ewcm, five days past my first positive opk even though the last two days have been negative and I was wondering if I hadn't been holding it long enough to show a positive and if the dark yellow urine is the color you should be testing with and if the paler yellow opks would be invalid. For all of the tests I held my urine for 2 and a half hours and I didn't have anything to drink within that time frame. The first day I had the positive I didn't have anything to drink for 4 hours because if work, then the second day I had a positive I had a sip to drink in the morning then nothing for 2 and a half hours.