Simple simulation, cannot get "generator" to work

Hello list,

I've just started reading about gnucap and it's a fascinating piece of 
software that I'd like to use. So I started up with a really, really 
simple "ciruit":

* Spice netlister for gnetlist
.generator amplitude=3.3 frequency=4.7k phase=0
Vcc (Vcc 0) generator(1)
R2 0 1 27
R1 Vcc 1 1k
C2 1 PROBE 100n
C1 0 1 1u
.END

And it works as I expect it to:

http://bildrian.de/n/b/668181cccf06a7d5.png

But when I change the frequency to 5kHz:

http://bildrian.de/n/b/8403223bee500f64.png

What am I doing wrong?

Thanks in advance,
Johannes