Openlayers - zooming to show multiple co-ordinates

I have a bunch of co-ordinates, and i was the map to show them all on screen
Currently, its just zooming on one asset

I've, found some code, but it just seems to zoom into the sea (near gulf of guinea), i'm not sure if this is due to a map type?

Here is my code that i've been using to try and get it working

var selectedAsset_Coordinates = {};
var markers = new OpenLayers.Layer.Markers("Markers");

selectedAsset_Coordinates.d = [];

for (var kd = 0; kd < currentlySelectedCheckboxes.length; kd++) {
            
            k = currentlySelectedCheckboxes[kd];

            selectedAsset_Coordinates.d[k] = {};
            selectedAsset_Coordinates.d[k].vLongitude = obj.d[k].vLongitude;
            selectedAsset_Coordinates.d[k].vLatitude = obj.d[k].vLatitude;

            var _CurrentRowId = $("#chk" + k)[0].id.substring(3, $("#chk" + k)[0].id.length);
            if ($.inArray(parseInt(_CurrentRowId), currentlySelectedCheckboxes) > -1) {
                var point = new OpenLayers.Geometry.Point(obj.d[k].vLongitude, obj.d[k].vLatitude);
                point = point.transform(WGS84, map.getProjectionObject());

                var pointFeature = new OpenLayers.Feature.Vector(point, null, null);

                var _str = ShortAssetName(obj.d[k].vDeviceName);

                pointFeature.attributes = {
                    label: _str,
                    favColor: 'blue', //favorite color
                    align: "cm",
                    labelAlign: "cm",
                    AssetID: obj.d[k].vpkDeviceID
                };


                flagLayer.addFeatures([pointFeature]);  // this code for showing tooltip


                //map.setCenter(new OpenLayers.LonLat(obj.d[k].vLongitude, obj.d[k].vLatitude).transform(WGS84, map.getProjectionObject()), map.getZoom());


            var ipoint = new OpenLayers.Geometry.Point(obj.d[k].vLongitude, obj.d[k].vLatitude);
            ipoint = ipoint.transform(WGS84, map.getProjectionObject());

           var ipointFeature = new OpenLayers.Feature.Vector(ipoint, null, null);

            ipointFeature.attributes = {
                icon: maparrow + obj.d[k].vImage,
                label: obj.d[k].vDeviceName,
                radius: 1,
                date: recevedtime,
                Ignition: obj.d[k].bIsIgnitionOn,
                Latitude: obj.d[k].vLatitude,
                Longitude: obj.d[k].vLongitude,
                AssetName: obj.d[k].vDeviceName,
                DriverId: obj.d[k].DriverId,
                AssetPhotoName: obj.d[k].AssetPhotoName,
                iTrackerType: obj.d[k].iTrackerType,
                FuelVoltage: obj.d[k].FuelVoltage,
                Drivername: obj.d[k].Drivername,
                DriverPhoto: obj.d[k].DriverPhoto,
                Speed: obj.d[k].vVehicleSpeed,
                AssetID: obj.d[k].vpkDeviceID,
                ipkAssetID: parseInt(obj.d[k].ipkDeviceID, "10")
            };

            markerLayer.addFeatures([ipointFeature]);


            markerLayer.addFeatures([ipointFeature]);
            MselectControl.select(this.markerLayer.features[kd]); }
            map.addLayer(markers);
           var size = new OpenLayers.Size(25, 25);
            var offset = new OpenLayers.Pixel(-(size.w / 2), -size.h);
            var icon = new OpenLayers.Icon('http://www.openlayers.org/api/img/zoom-world-mini.png', size, offset);
            markers.addMarker(new OpenLayers.Marker(new OpenLayers.LonLat(selectedAsset_Coordinates.d[k].vLongitude,            
selectedAsset_Coordinates.d[k].vLatitude), icon));

}

    //zoom to multiple co-ordinates
    map.zoomToExtent(markers.getDataExtent());
  

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as i said above, it zooms to the sea and not the co-ordinates
is there a better way/ other way/ error above?

HELP!