Error in a simple query

Hi,

I'm using psycopg2 extensively in different scripts to process spatial data
with postgresql 9.1 and postgis. However, in one script I have the following
error:

psycopg2.internalerror: current transaction is aborted, commands ignored until
end of transaction block

The command that gave the error is:

a = """select idbalizas from nuevo.balizas where %s %s %s %s""" % (emp1,
dnid1, mem1, mmsi1)
print
cur.execute(a)

One example of 'a' is:

select idbalizas from nuevo.balizas where emp='005' and dnid='08466' and
mem='055' and mmsi='701000535'

I can run this same query in psql and other postgresql clients and it returns
the correct answer.

Can you help me debugging this?
Many thanks.

--
Gustavo Martínez
Skype: gmpuljak
Linkedin: http://ar.linkedin.com/in/gustavomartínezpuljak

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