[Discuss-gnuradio] standard squelch crashing?

[davek]

im trying to implement standard squelch into one of my flowgraps however crashes when excuted.
 a test flowgraph null source -> squelch -> null sink heres what i get in top_block.py

##################################################

# Blocks
##################################################
self.blks2_standard_squelch_0 = -------->
cannot find 'set_threshold' while searching for 'set_threshold': blks2.standard_squelch(audio_rate=$audio_rate)

$id.set_threshold($threshold)
<--------
self.gr_null_sink_0 = gr.null_sink(gr.sizeof_float*1)
self.gr_null_source_0 = gr.null_source(gr.sizeof_float*1)


Any ideas?
dave