[Users] Zoomslider not working at IE8

[Sarah Schuessler]

Hi list,

I think that is an easy question but I`m stuck so hoping someone could give a 
hint.

I`m using gx_zoomslider at my map but only showing up at firefox. 
At IE I can see zoomslidertip and there is no red cross. 
Changing map.Z_INDEX_BASE['Control'] to a higher rate did not solve it.

Here is some code:

var view = new Ext.Viewport({
			layout: "border",
			items: [new Ext.BoxComponent({
                        		region: 'north',
                        		el: 'north',
                       			height: 40,
                       			margins: '0 0 5 5' 
				}),
				{title: "Karte",
				type: "gx_mappanel",
				id: "mappanel",					
				tbar: toolbarItems,					
				region: "center",
				margins: '0 0 0 5',
				map: map,
				layers: [ layerLand, layerLandkreise , layerTK, layerIMS2, layerWaldfunkt ],
				zoom: 0,
				items: [
					{ xtype: "gx_zoomslider", 
					vertical: true,
					height: 120,
					x: 20,
					y: 30,
					plugins: new GeoExt.ZoomSliderTip({
						template: "Massstab: 1 : {scale} "}) 

					}
				    ]

				},

Any hints?

Thanks
best regards
Sarah