Meta audience network test ad setup not working in ios

Question

I am not able to get test ads on my ios simulator. I already added below code before sdk initialization.

let key = FBAdSettings.testDeviceHash()
FBAdSettings.setLogLevel(FBAdLogLevel.log)
FBAdSettings.addTestDevice(key)

I am getting no fill. here is the error

Domain=com.facebook.ads.sdk Code=1001 "No fill" UserInfo={NSLocalizedDescription=No fill, FBAdErrorDetailKey={
    msg = "No fill";
}}

I've tried with this placement id IMG_16_9_LINK#{your-placement-id}.