Implicit conversion from data type sql_variant to uniqueidentifier is not allowed

I kept getting an error when updating my DataGrid control. Below is my SQLDataSource and Datagrid control:

<asp:SqlDataSource ID="sqlLusHmoob" runat="server"
        ConnectionString="<%$ ConnectionStrings:LaujTsovConnectionString %>"
        DeleteCommand="DELETE FROM [lusHmoob] WHERE [wordID] = @wordID"
        InsertCommand="INSERT INTO [lusHmoob] ([wordID], [word], [whoInsert], [approval], [hmgTrans], [engTrans], [usage]) VALUES (@wordID, @word, @whoInsert, @approval, @hmgTrans, @engTrans, @usage)"
        SelectCommand="SELECT [wordID], [word], [whoInsert], [approval], [hmgTrans], [engTrans], [usage] FROM [lusHmoob]"

        UpdateCommand="UPDATE [lusHmoob] SET [word] = @word, [whoInsert] = @whoInsert, [approval] = @approval, [hmgTrans] = @hmgTrans, [engTrans] = @engTrans, [usage] = @usage WHERE [wordID] = @wordID"><DeleteParameters><asp:Parameter Name="wordID" Type="Object" /></DeleteParameters><InsertParameters><asp:Parameter Name="wordID" Type="Object" /><asp:Parameter Name="word" Type="String" /><asp:Parameter Name="whoInsert" Type="Object" /><asp:Parameter Name="approval" Type="Boolean" /><asp:Parameter Name="hmgTrans" Type="String" /><asp:Parameter Name="engTrans" Type="String" /><asp:Parameter Name="usage" Type="String" /></InsertParameters><UpdateParameters><asp:Parameter Name="word" Type="String" /><asp:Parameter Name="whoInsert" Type="Object" /><asp:Parameter Name="approval" Type="Boolean" /><asp:Parameter Name="hmgTrans" Type="String" /><asp:Parameter Name="engTrans" Type="String" /><asp:Parameter Name="usage" Type="String" /><asp:Parameter Name="wordID" Type="Object" /></UpdateParameters></asp:SqlDataSource><asp:GridView ID="GridView1" runat="server" AllowPaging="True"
        AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="wordID"
        DataSourceID="sqlLusHmoob"><Columns><asp:CommandField ShowDeleteButton="True" ShowEditButton="True" /><asp:BoundField DataField="wordID" HeaderText="wordID" ReadOnly="True"
                SortExpression="wordID" /><asp:BoundField DataField="word" HeaderText="word" SortExpression="word" /><asp:BoundField DataField="whoInsert" HeaderText="whoInsert"
                SortExpression="whoInsert" /><asp:CheckBoxField DataField="approval" HeaderText="approval"
                SortExpression="approval" /><asp:BoundField DataField="hmgTrans" HeaderText="hmgTrans"
                SortExpression="hmgTrans" /><asp:BoundField DataField="engTrans" HeaderText="engTrans"
                SortExpression="engTrans" /><asp:BoundField DataField="usage" HeaderText="usage" SortExpression="usage" /></Columns></asp:GridView>

Here's the error:

Implicit conversion from data type sql_variant to uniqueidentifier is not allowed. Use the CONVERT function to run this query.

An unhandled exception was generated during the execution of the current
 web request. Information regarding the origin and location of the 
exception can be identified using the exception stack trace below.