Size of buttons in toolbar

Hello,
i have a toolbar which contains a button which has a size of 91x15 px.
How can i display this button propertly?
If i try it with the following code, only a button of i think 15x15 px is displayed:

Code:

---

hwndToolbar = CreateWindowEx(0,
                                TOOLBARCLASSNAME,
                                "Toolbar",
                                WS_CHILD | WS_VISIBLE | TBSTYLE_AUTOSIZE,
                                0, 15,
                                400, 15,
                                hwndMain,
                                (HMENU) ID_TOOLBAR,
                                NULL,
                                NULL);

---

Can you guys maybe help me?
Thank you.

Try sending the TB_SETBUTTONSIZE message.