OnCheckedChanged not taking effect immediately

Here's my code:
<asp:CheckBox ID="chkFinancialIndusRisk" runat="server" OnCheckedChanged="chkFinIndusRisk_CheckedChanged" AutoPostBack="true" />
protected void chkFinIndusRisk_CheckedChanged(Object sender, EventArgs e)         {             if (chkFinancialIndusRisk.Checked == true)                 txtFinIndustryRisk.Visible = true;             else                 txtFinIndustryRisk.Visible = false;         }
When I check the checkbox chkFinancialIndusRisk, I want the textbox txtFinIndustryRisk to immediately become visible.
What am I missing?
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