Dynamic plpgsql help

Hi

I have the following plpgsql function that works:

DROP TYPE if exists distr CASCADE;
CREATE TYPE distr AS (b bigint, var varchar);

DROP FUNCTION IF EXISTS dist() cascade;

CREATE or replace FUNCTION dist() RETURNS setof distr
AS $$ begin
  return query EXECUTE 'Select count(*) as b, cast(mostype as varchar)
as var from segmentation group by mostype';
end $$ LANGUAGE 'plpgsql' VOLATILE;
 ;

select * from dist();

When I try to make it dynamic, I get the error:

ERROR: column "mostype" does not exist

DROP TYPE if exists distr CASCADE;
CREATE TYPE distr AS (b bigint, var varchar);

DROP FUNCTION IF EXISTS dist(text) cascade;

CREATE or replace FUNCTION dist(text) RETURNS setof distr
AS $$ begin
  return query execute 'Select count(*) as b, cast( ' ||
quote_ident($1) || ' as varchar) as var from segmentation group by '
|| quote_ident($1);
end $$ LANGUAGE 'plpgsql' VOLATILE;
 ;

select dist(mostype);

Your help is appreciated

Scott