mes "Input item ID";
next;
input .@tmp, 0, 32767;
mes "["+ strnpcinfo(1) +"]";
if ( getitemname(.@tmp) == "null" ) {
mes "Invalid item ID";
next;
break;
Find this line and edit 32767 as I think it covers the maximum IDs it holds. I suppose you're using Item IDs more than 32767.
input .@tmp, 0, 32767;