Edit Xoml Workflow and Update workflow activities

Question

Hello,

I've created a workflow template using SharePoint designer. 
Then I have added some activities using C# in Visual studio to the xoml workflow file created by SharePoint Designer.

So I have replaced the old xoml file generated by SharePoint Designer with the new one contains additional activities.

Then I have updated the workflow template using  websvcWebPartPages web service in Microsoft SharePoint Foundation, the file has been updated successfully.

The problem is: The added activities didn't execute. 

Any idea?

Thanks in advance