c# - ComboBox selection returning IndexOutofBounds Error -

i setting such choice of first combobox(name = combo3) determines second combobox(name = combo4) show. works fine.

now trying make second combobox determine third combobox show. doesn't work. moment make selection on second combox, jams , returns error. if hard code value of 2nd combobox, works.

i getting indexoutofbounds exception. problem seems method private void combobox_selectionchanged2(). please advice wrong. thanks.

mainwindow

string[] tablearray = { "agent_name", "agent_age", "agent_gender", "agent_alias", "security_clearance", "dept_id", "job_id", "mission_id" }; string[] attributearray = { "mission_name", "mission_description", "mission_country", "mission_city" };  private void combobox_selectionchanged1(object sender, selectionchangedeventargs e)           {             if (((comboboxitem)combo3.selecteditem).content.tostring() == "agents")             {                 combo4.items.clear();                 foreach (string x in tablearray)                 {                     combo4.items.add(x);                 }             }             else             {                 combo4.items.clear();                 foreach (string x in attributearray)                 {                     combo4.items.add(x);                 }             }         }  private void combobox_selectionchanged2(object sender, selectionchangedeventargs e)         {             combo5.items.clear();             messagebox.show(combo4.text); //debugging line returns empty shouldn't case. chose mission_name should show mission_name.              //fillcombo("select * " + combo3.text + ";", "mission_name", combo5); //works                fillcombo("select * " + combo3.text + ";", combo4.text, combo5); // not working         }   private void fillcombo(string query, string name, combobox c)         {             mysqlcommand cmdreader = new mysqlcommand(query, conn);             mysqldatareader myreader;              myreader = cmdreader.executereader();              while (myreader.read())             {                 string temp = myreader.getstring(name);                 c.items.add(temp);             }             myreader.close();         } 

xaml:

<combobox x:name="combo3" width="120" selectionchanged="combobox_selectionchanged1">                 <comboboxitem x:name="box3" content="agents"/>                 <comboboxitem x:name="box4" content="missions"/>             </combobox>             <combobox x:name="combo4" width="120" selectionchanged="combobox_selectionchanged2">             </combobox> <combobox x:name="combo5" width="120" canvas.left="818" canvas.top="588"/> 

error message:

an unhandled exception of type 'system.indexoutofrangeexception' occurred in mysql.data.dll

additional information: not find specified column in results:

how combo boxes looks.

replace this

messagebox.show(combo4.text); 

with this:

messagebox.show(combo4.selectedtext); 

or this:

messagebox.show(combo4.selecteditem.tostring()); 

replace everywhere use combo4.text as-well combo1 2 3 , on