A question about rlm modules

Hello all I have written an rlm_module. It works fine. Here, we have clients which should be authenticated using CHAP passwords. In the radiusd.conf, I have mentioned my module before the CHAP module in the authentication section. Also, I have found that my module should populate the request->config_items field of the request with the clear text password so that the CHAP module can process the request. I have added the required code to do so, but the CHAP module complains about the size of the password. I want to know, is there something that I have missed? By the way, is the concept right at all? Thanks in advance. Regards Ali Majdzadeh