What,s wrong with this balun?

Hi everyone, I am dealing with a wideband balun covering from 3G~7GHz, to feed the LO of a SRD Mixer. I made the balun model according to some documents in HFSS environment. However, I was not able to add the balanced ports, and I added two waveports for them. And I get terrible results for the single balun. Anyone would like to tell me where I am wrong? The attachment is my simulation model.
By the way, the port impedance dropped from 46 Ohm to 32 Ohm, but the S(2,1) and S(1,1) are still like ideal for the back to back model. How to understand that?

Well， anyone could help me?