Error: sURL is undefined

Seems to happen here (and more specifically the line that reads var aURL, aSlides = sURL.split('|'):

// advanced popups
function dmxAdvLayerPopup(sTitle,sURL,sPopupName,sContent,sClass,nPositionLeft,nPositionRight,nWidth,nHeight,nAutoCloseTime,bDragable,bResizable,bOverlay,nOverlayOpacity,sIncomingEffect,sIncomingEffectEasing,nIncomingEffectDuration,bFadeIn,sOutgoingEffect,sOutgoingEffectEasing,nOutgoingEffectDuration,bFadeOut,sSlideEffect,nEffectTime,nSlideTime,bClosable,bWireframe,bgContentColor) { // v1.05
var aURL, aSlides = sURL.split('|');
if (aSlides && aSlides.length > 1) {
aURL = [];
for (var si=0;si<aSlides.length;si++) {
var cf=aSlides[si],nW='',nH='',nS='';
if (cf.substr(cf.length-1,1)==']') {
var bd=cf.lastIndexOf('[');
if(bd>0){
var di=cf.substring(bd+1,cf.length-1);
var da=di.split('x');
nW=da[0];nH=da[1];
if (da.length==3) nS=da[2];
cf=cf.substring(0,bd)
}
}
aURL[si] = new Object();
aURL[si].src = cf;
aURL[si].nWidth = (nW!=''?nW:nWidth);
aURL[si].nHeight = (nH!=''?nH:nHeight);
aURL[si].nDelay = (nS!=''?nS:nSlideTime);
}