在VS2005中调试Webservice

I am trying to debug a webservice by steping into a web method called
from a windows form project. The strange thing is that sometimes it
works but often it does not. When it does not work I get the following
error when trying to step into a web method:

Unable to automatically step into the server. The remote procedure
Could not be debugged. This usually indicaes that debugging has not
been enabled on the server. See help for @R_517_4045@ion.

Here is how my project looks like:

1) project: WinForm project which has a button that activates a web
method.
2) project: Web service which is consumed in project 1.

Solution -> Set Startup Project... -> Common Properties -> Startup
Project:
Multiple startup projects (注意：设置两个项目同时为启动项目)
1) entry: WebServiceProject (Action = Start)
2) entry: WinForm project (Action = Start)

Web.config is set to:
<compilation debug="true"/>
<authentication mode="Windows"/>

(注意：WebService项目的启动属性设置：等待外部程序请求再启动 )WebService project -> Property Pages -> Start OptionsDon't open a page. Wait for a request from an externalappplication.