We are having problems plotting grey tones in our office. The are coming out stippled instead of a shade. Does this have something to do with the Dither setting in the CTB?

For example we have the following for a grey tone set in a CTB?

Color: Use Object color
Dither: ON
Greyscale: ON
Pen #: Automatic
Virtual Pen: 252
Screening: 75%
Linetype: Use Object Line type
Adapative: off
Line Weight: .0254
Line End style: Use object
Line join style: Use Object
Fill Style: Use Object