c# - Textbox not displaying value after selecting from ComboBox Dropdown -

so have combo box , have list made using keyvaluepair<int, decimal>. want textbox have selected show value according key when select drop-down textbox.

relevant code:

// make list of truck weight , mpg. list<keyvaluepair<int, decimal>> weightmpg = new list<keyvaluepair<int, decimal>>();  private void mainform_load(object sender, eventargs e) {     decimal k = 7;     (int = 20000; < 40000; i+=1000){         weightmpg.add(new keyvaluepair<int, decimal>(i, k));         k -= 0.1m;     }     (int = 40000; < 45000; i+=1000){         weightmpg.add(new keyvaluepair<int, decimal>(i, 5));     }     weightmpg.add(new keyvaluepair<int, decimal>(46000, 4.9m));     weightmpg.add(new keyvaluepair<int, decimal>(47000, 4.8m));     weightmpg.add(new keyvaluepair<int, decimal>(48000, 4.7m));     truckweight2.datasource = weightmpg;     truckweight2.valuemember = "value";     truckweight2.displaymember = "key"; }  private void truckweight2_selectedindexchanged(object sender, eventargs e) {     truckmpg2.text = truckweight2.valuemember; } 

for code, shows dropdown 20,000 48,000 when click control. when select one, textbox (truckmpg2) doesn't update reflect value, rather displays word "value."

i've looked @ other stack-overflow answers when making code, i'm not sure going wrong.

you're reading .valuemember property:

truckmpg2.text = truckweight2.valuemember; 

which set literal string:

truckweight2.valuemember = "value"; 

it sounds want .selectedvalue property instead:

truckmpg2.text = truckweight2.selectedvalue; 

or, if type doesn't match value can directly represented string, might need append .tostring() value:

truckmpg2.text = truckweight2.selectedvalue.tostring();