# Error expressing Jack symmetric functions in terms of power sums

I'd like to express Jack symmetric functions in the J basis in terms of power sum symmetric functions. Here is an example of how I've been doing this.

```
F = FunctionField(QQ,"t")
Sym = SymmetricFunctions(F)
p = Sym.p()
JJ = Sym.jack().J()
p(JJ[3,3,1])
```

This example ^ works just fine. My issue is that once the partitions get to be a certain size (namely, 9), I get a key error.

```
F = FunctionField(QQ,"t")
Sym = SymmetricFunctions(F)
p = Sym.p()
JJ = Sym.jack().J()
for n in range(2,11):
for llambda in Partitions(n):
try:
p(JJ(llambda))
except KeyError:
print(llambda)
```

What exactly is going on here? Why can't [9,1], for example, be expressed in terms of power sum symmetric functions?

Works fine in Sage 10.3.beta7. Perhaps, it's time to update your version of Sage.