Band-pass filter with designfilt

I'm using designfilt to create a bandpass filter to meet a specification which has centre, 3dB and 20 dB frequency points.

The filter shape is narrower than a 2nd order butterworth filter, but wider than a 4th order filter.

The designfilt arguments include HalfPowerFrequency1 & 2, StopBandFrequency1 & 2, and StopBandAttenuation1 & 2.

My hope was that specifying these (with StopBandAttenuation... = 20) would work, but designfilt threw an error

d = designfilt('bandpassiir', 'StopbandFrequency1', 2400, 'HalfPowerFrequency1', 2424, 'HalfPowerFrequency2',
2436, 'StopbandFrequency2', 2460, 'StopbandAttenuation1', 20, 'StopbandAttenuation2', 20, 'SampleRate', 20000);
Error using designfilt (line 427)

(How) can I create such a filter?