Validation multiple checkbox form - asp.net-mvc

Question

in the page I have only three checkbox, the client should choose at least one before clicking on the submit button :
Controller :
[HttpPost]
public ActionResult Client(OrderItems model)
{
if (bValidated){
//Code here
}
else
{
model.itemChoosed = false;
return View("Client", model);
}
View Client :
#model WebApp.Models.OrderItems
#using (Html.BeginForm("Client", "Home", FormMethod.Post, new { #class = "form-group", role = "form" }))
{
#Html.AntiForgeryToken();
<h2>Client</h2>
#Html.Partial("SentMessage")
<div>
<div>
<h3>Item 1</h3>
<label>#Html.CheckBoxFor(model => model.CLInfo.Item1) Item 1</label>
</div>
<div>
<h3>Item 2</h3>
<label>#Html.CheckBoxFor(model => model.CLInfo.Item2) Item 2</label>
</div>
<div>
<h3>Item 3</h3>
<label>#Html.CheckBoxFor(model => model.CLInfo.Item3) Item 3</label>
</div>
</div>
<div class="row">
<input type="submit" name="action:Client" id="btnClient" class="btn btn-primary flat btn-large pull-right" value="Client" />
</div>
}
After I choose to put the condition into a Partail View :
Partial View SentMessage:
#model WebApp.Models.OrderItems
#if (!model.itemChoosed)
{
<div>You must choose at least one item</div>
}
I have the error message :
The view 'Client' or its master was not found or no view engine supports the searched locations. The following locations were searched:
~/Views/Home/Client.aspx
..
~/Views/Home/Client.cshtml
..
but Home/Client.cshtml existe since it's the view
Thanks