@edit: someone was faster.... -.-

Try this:

Code:
PANEL* menu_pan =
{
pos_x = 10;
pos_y = 340;
button(0,0,"button_new.bmp","button_new.bmp","button_new.bmp",DoReset,NULL,NULL);
layer=900; //to be sure nothing is above the panel
flags = VISIBLE;}

function DoReset() { ... } //You can write this function under the panel-definition also

//...
function main() {
mouse_mode=2;
mouse_map=bmap_create("button_new.bmp");
while(1)
{
vec_set(mouse_pos.x,mouse_cursor.x);
wait(1);}
//...


I do it that way, if I want to create a button on a panel.
If this isn't working also, try to use different bitmaps for the three button-states.
Hope I could help.

Hilf mir, dir zu helfen!