Exporting a graphic element with drop shadow and transparency - PNG

[hubris]

I'm having real troubles exporting a button which has drop shadow applied to it.

The vector shape has Gradient Overlay, Inner Shadow and Drop Shadow applied to it as layer effects.

When I export it with transparency, PNG-24 and then open and place it over the same background, the drop shadow looks quite different.

Is there a way to solve this?

Thanks a lot!

 

[hubris]

The drop shadow blending effect was set to Overlay.
Switching to Normal mode solved the issue.