I am working on asp.net web application.
In one Page I have two asp buttons.
I want to display them in one condition otherwise I don't want to display them.
So I'm trying to do the same like this. But Its not working.
I can't find the reason behind it. Please tell me where is the issue.

To Hide Buttons

if (!IsPostBack)

            {

                ButtonReplaceId.Style.Add(display, none);

                ButtonAssociateRules.Style.Add(display, none);

            }

To display buttons

protected void ApplyAssociation(object sender, EventArgs e)

{

//Some piece of code

if(a==0)

{

ButtonAssociateRules.Style.Add(display, block);

ButtonReplaceId.Style.Add(display, block);

}



}

aspx for buttons

    <div style =padding-left:400px;>

        <asp:Button ID=ButtonAssociateRules runat=server OnClick=AssociateMultipleRulesButtonClick

            CssClass=search_button_in_vm_intersection Text=Associate Multiple Rules 

            OnClientClick=return OnClientClickAssociateRewardRuleFile(); />



        <asp:Button ID=ButtonReplaceId runat=server OnClick=ApplyReplaceIfRuleIntersects

            CssClass=search_button_in_vm_intersection Text=Replace Previous Rules 

            OnClientClick=return OnClientClickReplaceRewardRuleFile(); />



    </div>

aspx of button for OnClick event ApplyAssociation()

<asp:UpdatePanel runat=server UpdateMode=Conditional>

                <Triggers>

                    <asp:AsyncPostBackTrigger ControlID=Button1 EventName=Click />

                </Triggers>

                <ContentTemplate>

                <asp:Table runat=server CssClass=rule_file_whole BorderWidth=0 Style=padding-top: 30px;>

                <asp:TableRow ID=MerchantRowAssociation HorizontalAlign=Center>

                            <asp:TableCell>

                                <div style=text-align: center>

                                    <asp:Button ID=AssociationMerchant Text=Apply Association runat=server OnClick=ApplyAssociation

                                        CssClass=search_button_in_vm_associate1  OnClientClick=return checkValidation() />

                                </div>

                            </asp:TableCell>

                        </asp:TableRow>

                                            </asp:Table>

                </ContentTemplate>

            </asp:UpdatePanel>