Multiband combiner block is atten the signal for no reason.

Greeting.

I am trying to simulate the interference of 2 signal by combine them using "Multiband Combniner Block" in simulink. as below diagram

First signal is very narrow band signal (carrier ~1 kHz) (Primary signal)

Second signal is wide band sigal (Carrier ~250 kHz) (Interfere signal)

Anyway, the spectrum for both Primary signal and Interfere sigal looks ok (as screenshot below)

but when I look at the spectrum after "Multiband Combiner" block, seems the interfere signal got attenuation around 60-70 dB in the spectrum analyzer.

And from the block configuration, I don't see any related on atten the signal.

What is the possible cause that my intefere signal is being attenuate and how can I fix this?

Best Regads,

Fumihiko Sato