Please try to do the following.

First, add the web service reference to the aspx page where you are planning to call this web service. In the aspx page inside form tag add following lines.

<asp:ScriptManager ID="MyService" runat="server">
    <Services>
        <asp:ServiceReference Path="~/GetUsers.asmx" />
    </Services>
</asp:ScriptManager>

Add script manager reference and add a service reference by adding a path to it. In the sample above, the service name is WebService.asmx.

Next, write the JavaScript function which calls the web service.

function FetchUsers(){    
    GetUsers.GetUsrs(OnWSRequestComplete, OnWSRequestFailed);
}

I enclosed a sample project as attachment. Please let us know whether it helps or not.

Thanks - this example works well.

Do you have an example where you pass data over to the WebService?  I would like to pass all of the checked rows in my grid back to the WebService - at least the ID of each row.

Thanks,

Dave

I made a minor modification to JavascriptWebService project by adding a method in the GetUsers class (the class file of GetUsers WebService) that has a single string parameter.

[WebMethod]
public string GetUsrs(string name)
{
    return name;
}

I simply invoke the method by using following line.

function FetchUsers()
{
    GetUsers.GetUsrs("test");
}

Hope this helps.