Giving Elements Layout

For Effect.Opacity based effects to work in Internet Explorer, you need to have give the affected elements the so-called ‘layout’ quality. The object that the filter is applied to must have layout before the filter effect displays.

You can give the object layout by doing one of the following:

· | Setting the height or width property (doesn’t work on inline elements when the browser is not in quirksmode but in standards-compliant mode)

· | Setting the display property to inline-block

· | Setting the position property to absolute

· | Setting the writingMode property to tb-rl

· | Setting the contentEditable property to true

Source: http://msdn.microsoft.com/workshop/author/filter/reference/filters/alpha.asp