NDK AdMob, Can't see admob on Framelayout

I added admob view to Android framelayout. 

I couldn't see ad. I think that admob view  is not disappered, because when I click admob location, actvity is changed to show advertisement.

To resolve problem, I applied background color to admob view. Below show my code.

Colored By Color Scripter™

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//-----------------------------------------------------------------------------------------------------------// //for admob adView = new AdView(this); adView.setAdSize(AdSize.SMART_BANNER); adView.setAdUnitId("ca-app-pub-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); layout.addView(adView, new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT,Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL));          AdRequest adRequest = new AdRequest.Builder() .addTestDevice(AdRequest.DEVICE_ID_EMULATOR) .addTestDevice("xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx") .build(); adView.loadAd(adRequest); adView.setBackgroundColor(Color.TRANSPARENT); //-----------------------------------------------------------------------------------------------------------//

I added [adView.setBackgroundColor(Color.TRANSPARENT);]. After applying this code, I could see admob test image.