Problem of Clicking in Button Of GridView

I have a gridview control . I Have a Added edit, delete, update, insert button. but update button works only when i double click on it . and also i am unable to change the page index when i click on index number of gridview. here is the code for gridview
<asp:GridView ID="gvDetails" runat="server" DataKeyNames="CategoryID,Name" AutoGenerateColumns="false" AllowPaging="true" AllowSorting="true" HeaderStyle-BackColor="#61A6F8" HeaderStyle-ForeColor="White" ShowFooter="true" Height="282px" OnRowCancelingEdit="gvDetails_RowCancelingEdit" OnRowCommand="gvDetails_RowCommand" OnRowDeleting="gvDetails_RowDeleting" OnRowEditing="gvDetails_RowEditing" OnRowUpdating="gvDetails_RowUpdating" Width="600px" PageSize="5" ForeColor="White" ...