altkey problem

To catch the altkey when pressing it, I added this code in winMain() :

Code:

---

while (!done)
    {
    //zoek boodschap
    if(PeekMessage(&msg, hwnd, 0, 0, PM_REMOVE))
    {
        if (msg.message == WM_QUIT)
        {
            done = 1;
        }
        else if (msg.message == WM_SYSKEYDOWN){
            G->ev->syskey |= SKY_ALT;
        }
        else if (msg.message == WM_SYSKEYUP){
            G->ev->key &= ~SKY_ALT;
        }
        else if (~(G->ev->syskey & SKY_ALT) )
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
    //...

---

A few lines further I added this code :

Code:

---

switch (G->ev->key)
    {
    case SKY_S:
        if (G->ev->syskey & SKY_SHIFT){
            //...
        }
        else if (G->ev->syskey & SKY_ALT){
            //...
        }
        else if (G->ev->syskey & SKY_CTRL){
            //...
        }
        break;

---

When CTRL and SHIFT are used, ther is no problem, everything works as supposed. But when ALT is used, there is a problem.

First of all, the code only works when I press 'S' first, and then 'ALT' .
Not when I press ALT first.
When it works, it works well, but when I release either 'S' or 'ALT', the program quits. Does anyone know how to resolve that ?

Thanks in advance