It seems that there's a bug - it doesn't allow you to set it to joined if the waveform being plotted already has the plotStyle set to "bar". This will be true of some waveforms coming from simulation, but not all - which is why it worked for me, but didn't work for Pancho Hideboo.
I'll file a CCR for this.
In the meantime, if you do this:
Code:Vif=getData("Pif")
Vif->plotStyle='joined ; could be set to nil too
plot( db20(Vif) ?expr '("Spectre") )
in your code, it will then work.
This workaround works regardless of using wavescan or AWD.
Regards,
Andrew.