w32api_deftype

Defines a type for use with other w32api_functions (PHP 4 >= 4.2.0)
bool w32api_deftype ( string typename, string member1_type, string member1_name [, string ... [, string ...]] )

nospam_ctramen

The variable types appear to be case sensitive, so byte, not BYTE. Also you use string, not CHAR.