Hello, guys.
I want to use DLL's functions in the script written in lite-C. However, the DLL isn't in the directory of 'acknex_plugins' so I had to call 'dll_open' in the main function. But while running the script, a window with the title of 'Malfunction W1521' pops up and said '...can't load DLL'. So obviously the function in DLL is still unknown for the script. It's very strange that the initializing engine window told me 'DLLtest.dll opened'. Btw, the DLL is built with VC6. The codes are just like this:

var i = 0;
function add(a,b); //'add(a,b)' is implemented in DLLtest.dll

function main()
{
dll_open("\\DLLtest\\Debug\\DLLtest.dll"); //the DLLtest.dll is in the current sub-dir of '\DLLtest\Debug'
wait(1);
video_mode = 7;
screen_color.blue = 150;
i = add(2,2);
}

Many thanks for replying and helping me!!