Block key "rtl2832_source" not found in Platform

Dear All,
I am new of SDR. I’ve read a lot and compiled Gnuradio and gr-baz on my
macbook snow leopard 10.6.8…but nothing, gnuradio doesn’t recognize
my ezcap as source…It’s a week that I try different combinations but i
really don’t understand what to change.
Can you help me?
Many Thanks

MacBook-di-Giulio:~ Giulio$ export

MacBook-di-Giulio:~ Giulio$
RuntimeWarning: compiletime version 2.6 of module ‘mtrand’ does not
match runtime version 2.7
from mtrand import *
<<< Welcome to GNU Radio Companion 3.3.0 >>>

Loading: “/Users/Giulio/rtl2832-fm.grc”

Error: Block key “rtl2832_source” not found in Platform - grc(GNU Radio
Traceback (most recent call last):
File “/opt/local/bin/gnuradio-companion”, line 51, in
256, 0))
GError: Icona gnuradio-grc non presente nel tema

Error: Connection between rtl2832_source_0(0) and
gr_freq_xlating_fir_filter_xxx_0(0) could not be made.
Traceback (most recent call last):
line 197, in import_data
assert(source_block_id in block_ids)


Showing: “/Users/Giulio/rtl2832-fm.grc”

Hi Giulio - It looks like GNU Radio is trying to mix and match between
Python 2.6 and 2.7. This, in general, is not advisable; try to coerce
GNU Radio into using one or the other. Fix that first, then see if
there’s still an issue. If so, maybe someone with knowledge of the
“rtl2832_source” can help. Good luck! - MLD