Effects disappear when object is on top of another

[displaced7]

I am trying to make a shadow effect on a floor plan (I do NOT want a directional shadow).  When I add an outer glow, it looks good on a white background, but when I move it on top of anything else (color/object, jpg, etc.) it disappears.

Is this a bug?  

(Note that the other shadows in the plan are png files, not created in Illustrator)

[Alessandro Anselmi · Accepted solution]

You can use the drop shadow at x:0 y:0 distance

or

make sure you have selected multiply as opacity method of your outer glow

[displaced7]

That ds trick worked, thanks!  Can't believe I didn't think of that before 😛

[displaced7]

fyi, the og effect was set to multiply