Syntax Error in COPY when “create function”

Am I forgetting some limitation?

I get " ERROR: syntax error at or near "$1"

SQL state: 42601 "with this

CREATE FUNCTION Import1() RETURNS text AS $$

DECLARE

path Char(100);

BEGIN

path = 'C:/zhl/hjs/anc_area.att';

COPY anc_areaAtt FROM path CVS;

RETURN path;

END;

$$ LANGUAGE plpgsql;

SELECT Import1() ;

But COPY can work well when I just put the string in the command:

CREATE FUNCTION Import2() RETURNS text AS $$

DECLARE

path Char(100);

BEGIN

COPY anc_areaAtt FROM 'C:/zhl/hjs/anc_area.att' CSV;

return path;

END;

$$ LANGUAGE plpgsql;

SELECT Import2() ;

Does this mean the "filename" in COPY command can not be a variable?

By the way, my OS is windowXP.

Thanks and Regards,
Hongliu