Bandwidth of AD8000 in non-inverting configuration

I have a AD8000 SOIC package in noninverting configuration (Fig. 50 datasheet). Rf=439 ohms, Rs=0ohms, RL is open circuit, Rg = open circuit, 0.1 uF decoupling caps at supply pins. I am using +/-5V supply. I am interested in the performance at 1.25 GHz. I use -20 dBm input and get -26 dBm output at 1.25 GHz. I don't think this matches the performance shown in Fig.5 of datasheet. Can you suggest what I could change to make it work as expected?