Problem in accessing the X-values of a signal waveform

Hello, 

I have this attached waveform that represents a frequency response of a model,

I am trying to find the frequency at where the output is maximum which represents for me the f2. the f1 I should find it as usual as for first-order circuits by multiplying the passband amplitude with 0.707 (which represent the - 3 dB), then f1 is the frequency at the resulted value.

I am trying to do it from Cadence calculator but looks like Xval function is not working,

for example Calculator is not giving me the Xval for the Ymax(Outputcap) to get f2, the same problem when trying to find f1

For your kind concern

Thank you