Problem authenticating if password contains a @

The brief overview, is that I'm trying to display the Admin GUI within the Windows C application, so when the user searches for a node, it displays a list within the app, then they can click on "Map Node" and it will bring up the GUI with the network map, using the node's IP address.

I was able to complete this in v9 using this syntax:

web_ltmview.Url = new Uri(

"https://" +

txt_username.Text +

":" +

System.Web.HttpUtility.UrlEncode(txt_password.Text) +

"@" +

ltmDerived +

".domain.com/" +

"tmui/Control/form?_form_holder_opener_=&handler" +

"=%2Ftmui%2Flocallb%2Fnetwork_map&handler_before=%2Ftmui%2Flocallb%2Fnetwork_map&showObjList=&showObjList_befor" +

"e=&hideObjList=&hideObjList_before=&enableObjList=partition_control&enableObjList_before=&disableObjList=&disa" +

"bleObjList_before=&form_page=%2Ftmui%2Flocallb%2Fnetwork_map.jsp&form_page_before=%2Ftmui%2Flocallb%2Fnetwork_" +

"map.jsp&error_page=%2Ftmui%2Flocallb%2Fnetwork_map.jsp&error_page_before=%2Ftmui%2Flocallb%2Fnetwork_map.jsp&s" +

"how_map=1&show_map_before=0&status_select_before=null&status_select=0&object_type_select_before=null&object_ty" +

"pe_select=&SearchString=" +

txt_serverIp.Text +

"&SearchString_before=*&irule_body_before=unchecked&Show+Summary_before=Show+Summary&Show+Map=Update+Map&Show+M" +

"ap_before=Update+Map"

);

I am unable to use that syntax in v10.

Any suggestions are much appreciated!