Can't select a client from clients list

I have a problem qith the clients list

Im using v. 1.5.1 of zen cart

the problem is that i cant pick an element of the managing clients list, only the last one, so i cant delete or edit any register, i have changed a few files for adding customer fields, such as includes/modules/create_account, templates/tpl_modules_create_account,
and anajal/customers

When i click over one of them the background color doesn´t change, and it doesn´t gives the client information, is like i haven´t done anything.

does anyone has an idea of what is the file that manages the list of clients?

TY!! :)

I have a problem qith the clients list

Im using v. 1.5.1 of zen cart

the problem is that i cant pick an element of the managing clients list, only the last one, so i cant delete or edit any register, i have changed a few files for adding customer fields, such as includes/modules/create_account, templates/tpl_modules_create_account,
and anajal/customers

When i click over one of them the background color doesn´t change, and it doesn´t gives the client information, is like i haven´t done anything.

does anyone has an idea of what is the file that manages the list of clients?

TY!! :)

i have changed a few files for adding customer fields
You might post the file names and the code you have altered??