>I did put it in the inputmask property but this column should accept negative and positive entries.
Did you include an additional digit for the minus sign? Minus 9 million needs the same amount of space as plus 99 million. I think the InputMask should be "##,###,###.##", for your example.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
