can't add custom fields

[gamesh]

Hello,

My setup:

SugarCRM community Edition 5.2.0j
Apache 2
Mysql 5.1
PHP 5.2.10

I can't seem to add custom fields in module builder. when i create a module, select BASIC type and open it's fields tab i can see the default felds but when i press add button and enter filed name, select type and press add the field does'nt appear in the fileds list tab.

am i doing something wrong?