HMC7043 unable to output normally when the frequency is higher than 1GHz

I want to fan out the clock with a maximum of 1.5GHz through hmc7043, and synchronize the outputs. But at present, it can only fan out 1GHz normally. When the input frequency is 1.1GHz, only the fundamental mode can be selected. Once the analog delay mode is selected, the output waveform is a mixture of various frequencies, which is very confusing. When the input frequency increases again, the fundamental mode can not output the waveform normally. Why is that?