Error 42601: No destination for result data. Using RefCursor

Help - I am going round in circles!
I am using the following method to call a POSTGRES function:

public DataTable rtnPatientDetails(int p_patientID)
{
DataTable v_userDT = new DataTable();
try
{
string v_connString = String.Format("Server={0};Port={1};User Id={2};Password={3};Database={4};", v_host, v_port, v_user, v_pass, v_dbName);

using (NpgsqlConnection v_connection = new NpgsqlConnection(v_connString))
{
// Open the PgSQL Connection.
v_connection.Open();
string v_functionName = "pat_getpatient";

using (NpgsqlCommand v_command = new NpgsqlCommand(v_functionName, v_connection))
{
using (NpgsqlTransaction v_tranaction = v_connection.BeginTransaction())
{
v_command.CommandType = CommandType.StoredProcedure;
v_command.Parameters.Add("id", p_patientID);
using (NpgsqlDataAdapter v_userDA = new NpgsqlDataAdapter(v_command))
{
v_userDA.Fill(v_userDT);
}
v_tranaction.Commit();
}
}
}
}
catch (NpgsqlException v_exception)
{
throw v_exception;
}
catch (Exception v_exception)
{
throw v_exception;
}
return v_userDT;
}

However the follow error is returned:

Error: 42601: query has no destination for result data:

The POSTGRES function I am calling is:

CREATE OR REPLACE FUNCTION pat_getpatient(int) RETURNS SETOF refcursor AS
$$
DECLARE
v_recordSet refcursor;
BEGIN
OPEN v_recordSet FOR
select * from v_patient where id=$1;
RETURN NEXT v_recordSet ;
return ;
EXCEPTION
WHEN OTHERS THEN
select inserterror( 'E', 'pat_rtnpatient', 'act_individual', substring(SQLERRM from 1 for 200)) ;
return ;
END;
$$
LANGUAGE plpgsql;

I have used this method many times with no problem. Previously where I have gotten the 42601 error it has usally been of the result of an error in my SQL.
But this time I cannot see one. The sql making up the view works fine (it was previously in the method). The view is:

create or replace view v_patient
AS
select a.id,
a.sal_id,
c.descr,
a.first_name,
a.middle_name,
a.surname,
a.known_name,
a.home_tel,
a.office_tel,
a.mobile,
a.email,
a.active,
d.mrn,
d.hospital_no,
TO_CHAR(d.dob, 'DD-MON-YYYY HH:MI:SS') AS "dob",
d.gender AS "gender_id",
e.descr AS "gender",
d.ward AS "ward_id",
i.descr AS "ward",
d.bed,
d.mothers_name,
d.fathers_name,
d.guardians_name,
d.premature,
d.fetal_echo,
d.ethnic_group_id,
f.descr AS "ethnic_group",
d.language_id,
g.descr AS "language",
TO_CHAR(d.presentation_date, 'DD-MON-YYYY HH:MI:SS') AS "presentation_date",
TO_CHAR(d.jpc_date, 'DD-MON-YYYY HH:MI:SS') AS "jpc_date",
TO_CHAR(d.last_seen_date, 'DD-MON-YYYY HH:MI:SS') AS "last_seen_date",
TO_CHAR(d.final_dc_date, 'DD-MON-YYYY HH:MI:SS') AS "final_ac_date",
d.blood_grp_id,
j.descr AS "blood_group",
d.referral_id,
k.descr AS "referral",
d.death_id,
l.descr as "death",
d.unit_id,
o.descr AS "medical_centre"
from act_individual a
left outer join act_type b on a.typ=b.id
left outer join act_salutation c on a.sal_id=c.id
right join act_patient d on a.id=d.id
left outer join maint_gender e on d.gender=e.id
left outer join maint_ethnic f on d.ethnic_group_id=f.id
left outer join maint_language g on d.language_id=g.id
left outer join maint_ward i on (d.unit_id=i.med_centre_id and d.ward=i.id)
left outer join maint_blood j on d.blood_grp_id=j.id
left outer join maint_referral k on d.referral_id=k.id
left outer join maint_death l on d.death_id=l.id
left outer join maint_medical_centre o on d.unit_id=o.id ;

42601 usually implies that there is no variable to put the result od the query in. But in me case I have defined one - 'refcursor'. I am lost can anyone see what is wrong?