since the copy paste solution was incomplete.
here is the better one to make it work you should first configure your
src\map\clif.c
then look for 20130320
// TODO: find a more accurate date for this
#if PACKETVER < 20130320
/// Request to buy item(s) from cash shop (CZ_PC_BUY_CASH_POINT_ITEM).
/// 0288 <name id>.W <amount>.W
/// 0288 <name id>.W <amount>.W <kafra points>.L (PACKETVER >= 20070711)
/// 0288 <packet len>.W <kafra points>.L <count>.W { <amount>.W <name id>.W }.4B*count (PACKETVER >= 20100803)
you should replace the 20130320 with your client version. just like 20120410
and find again 20130320
// TODO: find a more accurate date for this
#if PACKETVER >= 20130320
void clif_parse_cashshop_buy( int fd, struct map_session_data *sd ){
uint16 length = RFIFOW( fd, 2 );
uint16 count = RFIFOL( fd, 4 );
replace again the 20130320 with your client version. just like 20120410
and also add the packet on your packet_db.txt
add this line on the end of your client version. 20120410
// New cashshop
0x0844,2,cashshopopen,0
0x084a,2,cashshopclose,0
0x08c9,4,cashshopitemlist,0
0x0848,-1,cashshopbuy,0
then recompile.