问FS.Transform.createWriteStream转换函数失败，错误

EN

W20151211-14:38:38.240(5)? (STDERR) FS.Transform.createWriteStream transform function failed, Error: 
I20151211-14:38:38.242(5)? Exception in queued task: Error: cfs:graphicsmagick could not find "graphicsMagick" or "imageMagick"
I20151211-14:38:38.242(5)?     at gm (packages/cfs_graphicsmagick/packages/cfs_graphicsmagick.js:14:1)
I20151211-14:38:38.242(5)?     at Object.createSquareThumb (model/model.js:9:1)
I20151211-14:38:38.242(5)?     at packages/cfs_storage-adapter/packages/cfs_storage-adapter.js:355:1
I20151211-14:38:38.242(5)?     at addPassThrough (packages/cfs_storage-adapter/packages/cfs_storage-adapter.js:421:1)
I20151211-14:38:38.243(5)?     at [object Object].FS.Transform.createWriteStream (packages/cfs_storage-adapter/packages/cfs_storage-adapter.js:352:1)
I20151211-14:38:38.243(5)?     at Object.self.adapter.createWriteStream (packages/cfs_storage-adapter/packages/cfs_storage-adapter.js:171:1)
I20151211-14:38:38.243(5)?     at saveCopy (packages/cfs_worker/packages/cfs_worker.js:180:1)
I20151211-14:38:38.243(5)?     at Object.fsCollection.files.find.observe.added (packages/cfs_worker/packages/cfs_worker.js:42:1)
I20151211-14:38:38.243(5)?     at [object Object].observeChangesCallbacks.added (packages/minimongo/observe.js:153:1)
I20151211-14:38:38.243(5)?     at self.applyChange.added (packages/minimongo/observe.js:53:1)

var createThumb = function(fileObj, readStream, writeStream) {
  // Transform the image into a 10x10px thumbnail
  gm(readStream, fileObj.name()).resize('10', '10').stream().pipe(writeStream);
};

Images = new FS.Collection("images", {
  stores: [
    new FS.Store.FileSystem("thumbs", { transformWrite: createThumb }, {path: "~/uploads/thumbs"}),
    new FS.Store.FileSystem("images", {path: "~/uploads"}),
  ],
  filter: {
    allow: {
      contentTypes: ['image/*'] //allow only images in this FS.Collection
    }
  }
});

meteor add cfs:graphicsmagick