size of 0 would gives it no shadow... i suggest you look at your original artwork, perhaps object layer options in ID. it looks like an AI graphic, is there a layer in there perhaps?
one more thing... try applying the drop shadow to your object considering it has background and fill of none instead of the graphic.
Yes, it looks like you may have the drop shadow applied to both the Object and Graphic. Try changing the "Settings for:" to "Object" in the upper left of the dialog box and then alter the settings. Or just delete the object, place it again, and start over.
Europe, Middle East and Africa