Hi Barney! I recently cleaned two homes that had newly installed prefonished hardwood floors. I proceeded to clean as usual and moments later, as it dried, it was horribly streaky. So I switched to hot water with a few drops of dish soap and mopped again. Streaks again! Then I took a Terry cloth towel and buffed the floor dry as I mopped in sections. What a pain!!!
The good news about this is that the following month, when hired to clean it again, I found the streaking had mostly vanished and I could clean the floors as normal. I only found small sections that required buffing.
So that's my long-winded way of saying, mop with a little more water and a few drops of dish soap, then buff dry as you go for the first time cleaning. Afterwards, the problem should be resolved.