questions about semantic similarity notebook

[sunyi000]

Hi, I tried to replicate the semantic similarity notebook, using the same version of obo file and tair.gaf 2019-04-17

I got 0.0 for both Resnik and Lin score.. IC for the same term GO:0048364 is also different, I have 4.38057 and the example is 7

I'm quite new to this area , could you please shed some lights on why mine is different from the example?

Thanks