[postgis-users] Double type and Buffer

[Natalia]

Hi everybody!

    I need to use a BUFFER function (buffer (geometry,distance)) but i have 
a problem with the distance(double type). In the documentation, it's said that 
distance must be a double. I have done a explicit CAST to double 
precision but postgis says :
    "Function 'buffer(geometry, float8)' does not exist
Unable to identify a function that satisfies the given argument types
You may need to add explicit typecasts "

My query is:
    SELECT node_id
    FROM mytable
    WHERE within( the_geom ,BUFFER (
       GeometryFromText('LINESTRING(-0.0007 40.0216,-0.0006 40.5009)', -1) ,
       CAST (1000.01 as double precision)
       )   ) = 1

    I have also tried to put other numbers like 0.999999999, 0.99999, other 
CAST, creating a line and gets its length (because this function return 
a double) but the same error appears.
I'm using 7.2.1 version, the binary compiled for Windows2000.
Any idea?
Thanks in advance!
Natalia