Grid fills not aligning properly?

[Robbie]

I used to create grid sections and place them over my map strategically where I wanted them to appear, but after seeing the fancier maps, I'd like to use grid fills, or even scaled bitmaps with artistic tiles that represent the grid lines...only problem is, they never align with the grid.

Here's a picture of a stone floor multipoly, with a grid filled copy of the multipoly on top of it. The grey grid represent the actual grid of the map...the black lines are from the grid fill. Although I'm using the grid symbol fill here, I get the same issue with scaled bitmap images.

FOr example, if I had an image that consisted of 4 tiles (2x2) and I wanted each tile to represent 5' squares...I would scale the bitmap fill to 10' in theory...but when I do that, although its scaled correctly, it doesn't align with the grid whats the trick I'm missing?