LinkButton Click Event is not working in DetailsView

Hi,

Here I have created sample using your code,It is working fine.

HTML

<div>
    <asp:DetailsView ID="detailsview1" runat="server" GridLines="Vertical" AutoGenerateRows="False"
        HeaderStyle-BackColor="#FFFFFF" HeaderStyle-ForeColor="White" CellPadding="3"
        Height="50px" Width="446px" DataKeyNames="StoreNumber" BackColor="White" BorderColor="#cccccc"
        BorderStyle="None" BorderWidth="1px" ForeColor="Black" CommandRowStyle-Font-Overline="true">
        <Fields>
            <asp:TemplateField HeaderText="Store Number:" HeaderStyle-Font-Names="Tahoma">
                <ItemTemplate>
                    <asp:Label ID="lblStoreNum" ForeColor="#ff3300" runat="server" Text='<%# Bind("StoreNumber")%>'></asp:Label>
                </ItemTemplate>
                <HeaderStyle Font-Names="Tahoma" />
            </asp:TemplateField>
            <asp:TemplateField HeaderText="View Image">
                <ItemTemplate>
                    <asp:LinkButton ID="LinkButton1" runat="server" ToolTip="View Image" CommandName="storage"
                        CommandArgument='<%# Eval("StoreNumber")%>' OnCommand="OpenViewPdf_Command">
                        <asp:Image ID="Image4" runat="server" ImageUrl="~/Images/viewImg_.png" ImageAlign="Middle"
                            Width="20" Height="15" Style="border-width: 0px; margin-left: 25px" /></asp:LinkButton>
                </ItemTemplate>
                <HeaderStyle Font-Bold="False" Font-Names="tahoma" Font-Size="9pt" Width="75px" />
                <ItemStyle Font-Bold="False" Font-Names="tahoma" Font-Size="9pt" Width="75px" />
            </asp:TemplateField>
            <asp:TemplateField HeaderText="First Name:" HeaderStyle-Font-Names="Tahoma">
                <ItemTemplate>
                    <asp:Label ID="lblFName" ForeColor="#ff3300" runat="server" Text='<%# Bind("FirstName")%>'></asp:Label>
                </ItemTemplate>
                <HeaderStyle Font-Names="Tahoma" />
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Last Name:" HeaderStyle-Font-Names="Tahoma">
                <ItemTemplate>
                    <asp:Label ID="lblLName" ForeColor="#ff3300" runat="server" Text='<%# Bind("LastName")%>'></asp:Label>
                </ItemTemplate>
                <HeaderStyle Font-Names="Tahoma" />
            </asp:TemplateField>
        </Fields>
        <FooterStyle BackColor="#CCCCCC" />
        <HeaderStyle BackColor="Black" Font-Bold="True" ForeColor="White" />
        <PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
    </asp:DetailsView>
</div>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[] { 
            new DataColumn("StoreNumber"),
            new DataColumn("FirstName"),
            new DataColumn("LastName")
        });
        dt.Rows.Add(1, "David", "Morkel");
        dt.Rows.Add(2, "Kevin", "Morkel");
        detailsview1.DataSource = dt;
        detailsview1.DataBind();
    }
}

protected void OpenViewPdf_Command(object sender, CommandEventArgs e)
{
    string storenumber = e.CommandArgument.ToString();
    string popup = string.Format("window.open('http://ABC/files/{0}.pdf','_blank')", storenumber);
    ScriptManager.RegisterStartupScript(this, this.GetType(), "key", popup, true);
}

VB

Protected Sub Page_Load(sender As Object, e As EventArgs)
	If Not Me.IsPostBack Then
		Dim dt As New DataTable()
		dt.Columns.AddRange(New DataColumn() {New DataColumn("StoreNumber"), New DataColumn("FirstName"), New DataColumn("LastName")})
		dt.Rows.Add(1, "David", "Morkel")
		dt.Rows.Add(2, "Kevin", "Morkel")
		detailsview1.DataSource = dt
		detailsview1.DataBind()
	End If
End Sub

Protected Sub OpenViewPdf_Command(sender As Object, e As CommandEventArgs)
	Dim storenumber As String = e.CommandArgument.ToString()
	Dim popup As String = String.Format("window.open('http://ABC/files/{0}.pdf','_blank')", storenumber)
	ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "key", popup, True)
End Sub

I hope this will help you out.