window.showdialog传值问题，怎么获取不到呢


        var siteurl="http://school.sina.com.cn";
var arr = showModalDialog(siteurl+"/sbbs_editor/img.asp", window, "dialogWidth:440px; dialogHeight:360px; status:0; help:0");img.asp里的返回代码：  
function ReturnValue(){
sFromUrl = d_fromurl.value;
sAlt = d_alt.value;
sBorder = d_border.value;
sBorderColor = d_bordercolor.value;
sFilter = d_filter.value;
sAlign = d_align.value;
sWidth = d_width.value;
sHeight = d_height.value;
sVSpace = d_vspace.value;
sHSpace = d_hspace.value; if (sAction == "MODI") {
oControl.src = sFromUrl;
oControl.alt = sAlt;
oControl.border = sBorder;
oControl.style.borderColor = sBorderColor;
oControl.style.filter = sFilter;
oControl.align = sAlign;
oControl.width = sWidth;
oControl.height = sHeight;
oControl.vspace = sVSpace;
oControl.hspace = sHSpace;
}else{
var sHTML = '';
if (sFilter!=""){
sHTML=sHTML+'filter:'+sFilter+';';
}
if (sBorderColor!=""){
sHTML=sHTML+'border-color:'+sBorderColor+';';
}
if (sHTML!=""){
sHTML=' style="'+sHTML+'"';
}
sHTML = '<img src="'+sFromUrl+'"'+sHTML;
if (sBorder!=""){
sHTML=sHTML+' border="'+sBorder+'"';
}
if (sAlt!=""){
sHTML=sHTML+' alt="'+sAlt+'"';
}
if (sAlign!=""){
sHTML=sHTML+' align="'+sAlign+'"';
}
if (sWidth!=""){
sHTML=sHTML+' width="'+sWidth+'"';
}
if (sHeight!=""){
sHTML=sHTML+' height="'+sHeight+'"';
}
if (sVSpace!=""){
sHTML=sHTML+' vspace="'+sVSpace+'"';
}
if (sHSpace!=""){
sHTML=sHTML+' hspace="'+sHSpace+'"';
}
sHTML=sHTML+'>';
//IframeID.document.body.innerHTML=sHTML;
//dialogArguments.insertHTML(sHTML);
}
re = new makearray(3);
re[1]=sHTML;
re[2]=d_upfilename.value;
re[3]=fileid.value

alert(re[1]);  //这里有值的
window.returnValue = re;
window.close();
}我用另一个域名的页面调用，结果却取不到值，难道是说window.showdialog不能跨域返回值？