C Function returning a tuple with a float4 array as column

HI,

Anyone have any ideas what wrong with my C code to return a tuple with
1 column that is a float4 array. I have tested functions returning a
float4 array and a row and both work independently. When I combine the
code I get the SQL error

ERROR: cache lookup failed for type 0

********** Error **********

ERROR: cache lookup failed for type 0
SQL state: XX000

from the SQL query

select pg_backend_pid(), getrecordarray();

The function is defined

create or replace function GetRecordArray() returns table (
Param_1 real[]
)
AS .....
LANGUAGE C STRICT;

The C code is

PG_FUNCTION_INFO_V1(GetRecordAray);
/**
GetRecordArray Function to return a record with 1 column as a
Float4 array
@returns record with a float4 array
**/
DLLEXPORT Datum GetRecordArray(PG_FUNCTION_ARGS)
{
Datum column[1]; /* Columns for the record */
bool isNULL[1] = { false };
Datum results; /* Results tuple */
HeapTuple tuple; /* Record Tuple */
TupleDesc tupleDesc; /* Tuple descripton */

float dataArray[2] = { 1.1f, 3.1e-16f };
ArrayType * arrayType;
Datum *datum;
int16 typlen;
bool typbyval;
char typalign;

datum = (Datum *)palloc(sizeof(Datum) * 2);

datum[0] = Float4GetDatum(dataArray[0]);
datum[1] = Float4GetDatum(dataArray[1]);

get_typlenbyvalalign(FLOAT4OID, &typlen, &typbyval, &typalign);
arrayType = construct_array(datum, 2, FLOAT4OID, typlen,
typbyval, typalign);

/* Create and bless the template */
tupleDesc = CreateTemplateTupleDesc(1, false);

TupleDescInitEntry(tupleDesc, (AttrNumber) 1, "Param_1",
FLOAT4ARRAYOID, -1, 0);

tupleDesc = BlessTupleDesc(tupleDesc);

/** Set up the column Datum for the Tuple **/
column[0] = DatumGetPointer(arrayType);

/** Build the tuple **/
tuple = heap_form_tuple(tupleDesc, column, isNULL);
results = HeapTupleGetDatum(tuple);

PG_RETURN_DATUM(results);

}