radius server

i have microsoft server 2003,small business standard edition. i downloaded tekradius,micorosoft sql 2005,microsoft.net framework 2.0.
this is the problem:
the server radius is running.
sql 2005 server is running.
but i cannot connect to sql server from the tekradius server: it is telling me that sql connection failed or login failed.
please any can tell me what is wrong?
thank you.