Loscil or i'm crazy ?

Dear all,
I think I'm gonna be crazy. I'm using the below csd, but out amplitude is 0.
Now i'm a little bit tired and i don't know if i'm wrong or i'm sleeping.
Please tell me somethings (about csd, not me, thanks!)

<CsoundSynthesizer>
<CsOptions>
</CsOptions>
<CsInstruments>

sr      = 48000
ksmps   = 128
nchnls  = 2
0dbfs = 32767

instr 1

a1, a2 loscil 20000, 1, 1, 1, 1

outs a1, a2
endin

</CsInstruments>
<CsScore>

f1  0  0  1  "audio_1e10.wav"  0  0  0
i1 0 20
e
</CsScore>
</CsoundSynthesizer>

What happens? It seems to me that loscil was working well ...

ciao,
always thanks,

sleepy fran.