Populate DataGrid from dynamic DropDown

Wow, it really sucks when you are trying to learn something and it just seems to not want to come together!

Anyways, my problem is this: I have a couple DropDownLists that are being populated from a database. Once the page loads, I am trying to set it up where the user can select an item from the DropDown, and then using a value associated the item in the DropDown, search the database again, and pull all matching records and place them in a DataGrid.

My code looks something like this:

<script runat="server"
Sub Page_Load(Source As Object, E As EventArgs)
 If Not Page.IsPostBack Then
 StatesDropDownList()
 End IF
End Sub
Sub StatesDropDownList()
 Dim strConnection As String = "Provider=Microsoft.Jet.OleDb.4.0;data source=" & Server.Mappath("\data\globalresorts.mdb")
 Dim objConnection As New OleDbConnection (strConnection)
 Dim strSqlStates As String = "SELECT DISTINCT State FROM Properties"
 Dim objCommand As New OleDbCommand(strSqlStates, objConnection)
 Dim objReader As OleDbDataReader = Nothing
 objConnection.Open()
 objReader = objCommand.ExecuteReader()
 ddlStatesFilter.DataSource = objReader
 ddlStatesFilter.DataTextField = "State"
 ddlStatesFilter.DataValueField = "State"
 ddlStatesFilter.DataBind()
 objConnection.Close()
Dim DefaultState As ListItem = New ListItem
DefaultState.Text = "Select a State"
DefaultState.Value = "0"
ddlStatesFilter.Items.Insert(0, DefaultState)
End Sub
Sub DoSearch(Source as Object, E as EventArgs)
Dim strStates As String = ddlStatesFilter.SelectedItem.Value
 Dim strConnection As String = "Provider=Microsoft.Jet.OleDb.4.0;data source=" & Server.Mappath("\data\globalresorts.mdb")
 Dim objConnection As New OleDbConnection(strConnection)
 Dim strSQL As String = "SELECT * FROM Properties WHERE State =" & ddlStatesFilter.SelectedItem.Value & " ORDER BY ID"
 Dim objAdapter as New OleDbDataAdapter(strSQL, objConnection)
 Dim objDataSet As New DataSet()
 objAdapter.Fill(objDataSet, "dtProperties")
dgProperties.PagerStyle.NextPageText = "Next"
dgProperties.PagerStyle.PrevPageText = "Previous"
 dgProperties.DataSource = objDataSet.Tables.Item("dtProperties")
 dgProperties.DataBind()
End Sub
</script>

And then the control and the DataGrid look a little something like this:

<form runat="server>
<asp:literal ID="lbStatesFilter" runat="server" Text="State: " />
<asp:dropdownlist ID="ddlStatesFilter" runat="server" Font-Names="Verdana" Font-Size="8pt" />
<asp:button ID="SubmitSearch" runat="server" OnClick="DoSearch" Text="Search Listings" Font-Names="Verdana" Font-Size="8pt" Width="150" />
<asp:Datagrid id="dgProperties" runat="server"
AutoGenerateColumns="false"
Font-Size="8pt"
CellPadding="8"
AlternatingItemStyle-BackColor="#CCCCCC"
Font-Names="Verdana"
Width="100%"
AllowPaging="True"
OnPageIndexChanged="GridPageChange"
PageSize="20">
<HeaderStyle font-bold="True" forecolor="White" backcolor="#005BAC"></HeaderStyle>
<EditItemStyle backcolor="WhiteSmoke"></EditItemStyle>
<AlternatingItemStyle backcolor="Gainsboro"></AlternatingItemStyle>
<ItemStyle backcolor="WhiteSmoke"></ItemStyle>
<Columns>
<asp:BoundColumn DataField="ID" HeaderText="ID" DataFormatString="{0:N0}" />
<asp:hyperlinkcolumn HeaderText="Resort Name" datanavigateurlfield="ID" datanavigateurlformatstring="details.aspx?id={0}" datatextfield="Resort_Name" />
<asp:BoundColumn DataField="City" HeaderText="City" />
<asp:BoundColumn DataField="State" HeaderText="State" />
<asp:BoundColumn DataField="Bedrooms" HeaderText="Bedrooms" />
<asp:BoundColumn DataField="Week" HeaderText="Week" />
<asp:BoundColumn DataField="Sale_Price" HeaderText="Sale Price" DataFormatString="{0:c2}" />
<asp:BoundColumn DataField="Rent_Price" HeaderText="Rent Price" DataFormatString="{0:c2}" />
</Columns>
</asp:Datagrid>
</form>

And here is the error that I am getting when I try and run it:

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Data.OleDb.OleDbException: No value given for one or more required parameters.
Source Error:
Line 149:
Line 150: Dim objDataSet As New DataSet()
Line 151: objAdapter.Fill(objDataSet, "dtProperties")
Line 152:
Line 153:dgProperties.PagerStyle.NextPageText = "Next"
Source File: D:\...\search.aspx Line: 151

Thanks in advance for any help on this one. And sorry for so much code, but Im just not sure where the problem is coming from, so I want to make sure I give all the facts.

-JasonWithout looking at your code, basic concpets.
On page load, populate the drop down lists, enclose this in the If Page.IsPostBack = False, so it only happens once, obviously this can change based on your requirements.
Next, have a method that populates the datagrid, such as the dropdownlist selectedindexchange. Just use the selectedindex, value to hit the database to populate the datagrid.