You cannot used the Helper @Html.DropdownListFor
, because the first parameter was not correct, change your helper to:
@Html.DropDownList("accountid", new SelectList(ViewBag.Accounts, "AccountID", "AccountName"))
@Html.DropDownListFor
receive in the first parameters a lambda expression in all overloads and is used to create strongly typed dropdowns.
Here’s the documentation
If your View it’s strongly typed to some Model you may change your code using a helper to created a strongly typed dropdownlist, something like
@Html.DropDownListFor(x => x.accountId, new SelectList(ViewBag.Accounts, "AccountID", "AccountName"))