basic temp table question

Hello,

 

The first time I run a query against this function (using Npgsql):

 

declare
       r_cursor1 cursor for

 

       SELECT * from tmp_table;

 

begin

 

       CREATE TEMPORARY TABLE tmp_table
        (
              testcol integer
        ) ON COMMIT DROP;

 

       INSERT INTO tmp_table
       SELECT 0;

 

       open r_cursor1;
 
       return 0;
end;

 

I get this error: