asp.net mvc - Unable to display MultiSelectList.SelectedValues on MVC view -

i working mvc application legacy code. far, changes made 2 calls retrieve lists of accountdivisionmodel objects. original code called stored procedures , returned objectresult, contained data.

public class accountdivisionmodel {     int divisionid;     string divisionname;     int accountid;     bool isactive; } 

i'm making 2 calls retrieve list of divisions belong account , list of (selected) divisions belong contact of account.

var adivs = account.getdivisionbyaccountid(c.accountid).toarray(); var cdivs = contact.getdivisionbycontactid(c.contactid).toarray(); viewbag.accountdivisions = new multiselectlist(adivs, "divisionid", "divisionname", cdivs); 

in edit view

@html.dropdownlist("accountdivisions", null, htmlattributes: new { @class = "form-control", @multiple = "multiple", @placeholder = "select division(s)" }) 

i don't know why selectedvalues not showing though when click on text box (@placeholder), can see populate drop down list divisions.

what have done wrong?

below image of current working interface. can see, selected values displayed in box , drop down list showing remaining items have not been selected.

the 4th argument of multiselectlist needs collection of selected values (usually int or string) match type of second parameter. passing collection of complex objects not match option value. solve changing

var cdivs = contact.getdivisionbycontactid(c.contactid).toarray(); 

to

var cdivs = contact.getdivisionbycontactid(c.contactid).select(c => c.divisionids); 

however recommend including property in model representing selected divisions allows 2 way binding

model

public ienumerable<int> selecteddivisions { get; set; } 

controller

model.selecteddivisions = contact.getdivisionbycontactid(c.contactid).select(c => c.divisionid); viewbag.accountdivisions = new multiselectlist(adivs, "divisionid", "divisionname"); // 4th parameter not required 

view

@html.listboxfor(m => m.selecteddivisions, (multiselectlist)viewbag.accountdivisions, new { @class = "form-control"}) // listboxfor adds multiple attribute 

the model contains selected values on post back.