How do I use the MapFish print engine for the GeoServer-GeoWebCache layer?

I am developing a webGIS application using GeoServer (2.1.1), GeoWebCache (1.2.6), OpenLayers (2.11), GeoExt. All my layers serve wms via GeoWebCache. The sample definition for any level is as follows:

 var My_Layer = new OpenLayers.Layer.WMS( "My_Layer",
            "http://my-ip + my-port/geoserver/gwc/service/wms",
            {layers: 'layer-name',transparent: "true",format: "image/png",
             tileSize: new OpenLayers.Size(256,256),
             tilesOrigin : map.maxExtent.left + ',' + map.maxExtent.bottom },
            { isBaseLayer: false, visibility:false} );

      

        
        
        
      

    

Everything worked fine up to this point. But, when I was planning to go ahead a bit and tried to implement MapFish Printing module, the output pdf is empty !!! I am getting the following error:

java.io.IOException: Error (status = 400) while reading image from ........

I've searched a lot. According to this one option is to access my layers as a TMS layer. But I don't want a static image layer, not a GeoServer WMS map layer.

Again, another option here is using OpenLayers.Control.ExportMap (). But this limits the use of different scales as my data is too big. As a result, at a specific scale, if the user wants to make a printout of an entire area of ​​the map (maybe on A0 paper) that is not fully displayed in the Openlayers div, this cannot solve the purpose.

So the question is, how can I do this without using the TMS tier or GeoWebCache?

Edit # 1: Sorry I'm running late as I was out of the office. Below is the config.yaml file. I feel like there are no errors, this can print my WMS layers coming directly from the GeoServer.

dpis: [75, 150, 300]

outputFormats:
  - pdf

scales:
  - 10000
  - 25000
  - 50000
  - 100000

hosts:
  - !localMatch
    dummy: true
  - !ipMatch
    ip: www.camptocamp.org
  - !dnsMatch
    host: labs.metacarta.com
    port: 80
  - !dnsMatch
    host: terraservice.net
    port: 80
  - !dnsMatch
    host: sigma.openplans.org
  - !dnsMatch
    host: demo.mapfish.org

layouts:
  A4 portrait:
    metaData:
      title: 'Arunava TopoMap PDF'
      author: 'Arunava print module'
      subject: 'Map layout'
      keywords: 'map,print'
      creator: 'Arunava'
    mainPage:
      pageSize: A4
      rotation: true
      items:
        - !text
          text: '${mapTitle}  ${now MM.dd.yyyy}'
          fontSize: 20
          spacingAfter: 30
        - !map
          spacingAfter: 30
          width: 440
          height: 600
        - !scalebar
          type: bar
          maxSize: 100
          barBgColor: white
          fontSize: 8
          align: right
        - !text
          font: Helvetica
          fontSize: 9
          align: right
          text: '1:${scale}'
      footer: *commonFooter

  A2 portrait:
    metaData:
      title: 'Arunava TopoMap PDF'
      author: 'Arunava print module'
      subject: 'Map layout'
      keywords: 'map,print'
      creator: 'Arunava'
    mainPage:
      pageSize: A2
      rotation: true
      items:
        - !text
          text: '${mapTitle}  ${now MM.dd.yyyy}'
          fontSize: 20
          spacingAfter: 30
        - !map
          spacingAfter: 30
          width: 880
          height: 1200
        - !scalebar
          type: bar
          maxSize: 100
          barBgColor: white
          fontSize: 8
          align: right
        - !text
          font: Helvetica
          fontSize: 9
          align: right
          text: '1:${scale}'
      footer: *commonFooter