Apply a link to a button in a layer by clicking on a hotspot

hello all,

I know how to change the image
in a layer (the layer is named "toggelbutton") when clicking on a
hotspot (the hotspot is named "spotpoint31"):

<action name="onclickspotpoint31">
set(layer[togglebutton].url, %FIRSTXML%/graphics/togglebutton/button_mini_ramp.png);
</action>

But how can I change also the link of this new button?

I tried it like this, without success:
<action name="onclickspotpoint31">
set(layer[togglebutton].url, %FIRSTXML%/graphics/togglebutton/button_mini_ramp.png);
set(layer[togglebutton].mainloadscene(pano22);
</action>

thank you!