While trying some experiment about beta distributions I found thid weird behaviour…

This code works :

```
with pm.Model() as model:
r0 = pm.Beta('r0',alpha=1+60,beta=1+60)
trace = pm.sample(chains=1)
_ = pm.traceplot(trace)
```

,

But this one, just changing the alpha & beta params from 60 to 70 :

```
with pm.Model() as model:
r0 = pm.Beta('r0',alpha=1+70,beta=1+70)
trace = pm.sample(chains=1)
_ = pm.traceplot(trace)
```

fails with a : *“ValueError: Bad initial energy: nan. The model might be misspecified.”*

I don’t understand why !? And this is even more strange :

`r0 = pm.Beta('r0',alpha=1+999,beta=1+999)`

works !!

Why certain specific parameter values range seem to have problem ?

Any help appreciated.