This is not the right forum, since it's not a PHNL support forum and, of course, if you posted in the right section (PHNL for FS9 or PHNL for FSX), it might have been possible to know which version you were referring to, even if you haven't mentioned in your message. After you clarify this, we'll move the message in the correct section.
In any case, if by "shimmering" you mean textures that flickers when the view moves, and since you noticed on fences specifically, IF you are referring to FS9, it's probably a too high setting on the MipMap quality slider. Putting it all the way to the right ( the 8 value ) will cause shimmering, a more sensible value is 5 or 6.
Also, try to use Anisotropic filtering on the Video card control panel.
In some cases, this can be caused by the lack of MipMap in the scenery textures, but PHNL and all our sceneries, always have MipMaps, just to prevent shimmering.