Hi kankon,

Check this sample. now take its reference and correct your code.

you need give expression for that column textbox in report.rdlc

i.e

=IIf(Fields!Country.Value = "USA", "ریاستہائے متحدہ", 
	IIf(Fields!Country.Value = "Austria","آسٹریا", 
	IIf(Fields!Country.Value = "UK", "متحدہ سلطنت یونائیٹڈ کنگڈم", Fields!Country.Value)
	)
)

HTML

<asp:DropDownList ID="ddlCountries" runat="server" OnSelectedIndexChanged="SelectedCountryChanged"
    AutoPostBack="true" Font-Size="Large">
    <asp:ListItem Text="All" Value="" />
    <asp:ListItem Text="مهندس كهرباء" Value="Austria" />
    <asp:ListItem Text="اشرافي/ مساعد مهندس (كهرباء)" Value="France" />
    <asp:ListItem Text="فني كهرباء" Value="Brazil" />
    <asp:ListItem Text="مهندس مدني" Value="Ireland" />
    <asp:ListItem Text="اشرافي/ مساعد مهندس مدني" Value="Italy" />
    <asp:ListItem Text="فني مدني" Value="Finland" />
    <asp:ListItem Text="مهندس ميكانيك" Value="mechanical1" />
    <asp:ListItem Text="اشرافي/ مساعد مهندس  ميكانيك" Value="mechanical2" />
    <asp:ListItem Text="فني ميكاكنيك" Value="mechanical3" />
    <asp:ListItem Text="مهندس زراعة / نظافة / خدمات فندقية" Value="adaptation1" />
    <asp:ListItem Text="اشرافي/ مساعد مهندس زراعة / نظافة / خدمات فندقية" Value="adaptation2" />
    <asp:ListItem Text="فني زراعة / نظافة / خدمات فندقية" Value="adaptation3" />
    <asp:ListItem Text="مهندس حاسوب / الكترونيات / اتصالات" Value="computer1" />
    <asp:ListItem Text="اشرافي/ مساعد مهندس حاسوب / الكترونيات / اتصالات" Value="computer2" />
    <asp:ListItem Text="فني حاسوب / الكترونيات / اتصالات" Value="computer3" />
</asp:DropDownList>
<hr />
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<rsweb:ReportViewer ID="ReportViewer1" runat="server" Width="500" SizeToReportContent="true"
    ZoomMode="PageWidth">
</rsweb:ReportViewer>

Namespaces

C#

using System.Configuration;
using System.Data.SqlClient;
using Microsoft.Reporting.WebForms;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient
Imports Microsoft.Reporting.WebForms

Code

C#

private void BindReport()
{
    ReportViewer1.ProcessingMode = ProcessingMode.Local;
    ReportViewer1.LocalReport.ReportPath = Server.MapPath("~/Report.rdlc");
    Customers dsCustomers = GetData(ddlCountries.SelectedItem.Value);
    ReportDataSource datasource = new ReportDataSource("Customers", dsCustomers.Tables[0]);
    ReportViewer1.LocalReport.DataSources.Clear();
    ReportViewer1.LocalReport.DataSources.Add(datasource);
}


protected void SelectedCountryChanged(object sender, EventArgs e)
{
    this.BindReport();
}

private Customers GetData(string country)
{
    string conString = ConfigurationManager.ConnectionStrings["NORTHWINDConnectionString"].ConnectionString;
    using (SqlConnection con = new SqlConnection(conString))
    {
        using (SqlCommand cmd = new SqlCommand("SELECT CustomerID,ContactName,City,Country FROM Customers WHERE Country = @Country OR @Country IS NULL", con))
        {
            cmd.Parameters.AddWithValue("@Country", !string.IsNullOrEmpty(country) ? country : (object)DBNull.Value);
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                using (Customers dsCustomers = new Customers())
                {
                    sda.Fill(dsCustomers, "DataTable1");
                    return dsCustomers;
                }
            }
        }
    }
}

VB.Net

Private Sub BindReport()
    ReportViewer1.ProcessingMode = ProcessingMode.Local
    ReportViewer1.LocalReport.ReportPath = Server.MapPath("~/Report.rdlc")
    Dim dsCustomers As Customers = GetData(ddlCountries.SelectedItem.Value)
    Dim datasource As ReportDataSource = New ReportDataSource("Customers", dsCustomers.Tables(0))
    ReportViewer1.LocalReport.DataSources.Clear()
    ReportViewer1.LocalReport.DataSources.Add(datasource)
End Sub

Protected Sub SelectedCountryChanged(ByVal sender As Object, ByVal e As EventArgs)
    Me.BindReport()
End Sub

Private Function GetData(ByVal country As String) As Customers
    Dim conString As String = ConfigurationManager.ConnectionStrings("NORTHWINDConnectionString").ConnectionString
    Using con As SqlConnection = New SqlConnection(conString)
        Using cmd As SqlCommand = New SqlCommand("SELECT CustomerID,ContactName,City,Country FROM Customers WHERE Country = @Country OR @Country IS NULL", con)
            cmd.Parameters.AddWithValue("@Country", If(Not String.IsNullOrEmpty(country), country, CObj(DBNull.Value)))
            Using sda As SqlDataAdapter = New SqlDataAdapter(cmd)
                Using dsCustomers As Customers = New Customers()
                    sda.Fill(dsCustomers, "DataTable1")
                    Return dsCustomers
                End Using
            End Using
        End Using
    End Using
End Function

Screenshot

in your case the expression will be.

=IIf(Fields!BlockSpecial.Value = "electrical1", "مهندس كهرباء", 
        IIf(Fields!BlockSpecial.Value = "electrical2","اشرافي/ مساعد مهندس كهرباء", 
        IIf(Fields!BlockSpecial.Value = "electrical3", "فني كهرباء", Fields!BlockSpecial.Value)
    )
)