Let say I have Table in Azure Table Storage

public class MyTable
{
  public string PK {get; set;}
  public string RowPK {get; set;}

  public double Amount {get; set;}
}

And message in Azure Queue which says Add 10 to Amount.

Now let say one worker role

1. Takes this message from queue
2. Takes row from table
3. Amount += 10
4. Updates Row in Table
5. And Fails

After a while message is available in queue again. So next worker role:

1. Takes this message from queue
2. Takes row from table
3. Amount += 10
4. Updates Row in Table
5. Removes message from queue

Those actions results in Amount += 20 instead of Amount += 10.

How can I avoid such situations?