unable to login when using user instance=true

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C#

.NET

private void button1_Click(object sender, EventArgs e)
        {
        
            SqlConnection con = new SqlConnection();
            con.ConnectionString = "database=test;server=.\\sqlexpress;integrated security=true; user instance=true; user=user;password=passwd";
            con.Open();
            SqlCommand cmd=new SqlCommand();
            cmd.Connection = con;
            cmd.CommandType=CommandType.Text;
            cmd.CommandText="insert into tbemp(Name,Address,Salary) values(@nm,@ad,@sal)";
            cmd.Parameters.Add("@nm",SqlDbType.VarChar,50).Value=textBox1.Text;
            cmd.Parameters.Add("@ad",SqlDbType.VarChar,50).Value=textBox2.Text;
            cmd.Parameters.Add("@sal",SqlDbType.VarChar,50).Value=textBox3.Text;
            cmd.ExecuteNonQuery();
        }

Cannot open database "test" requested by the login. The login failed.
Login failed for user 'user-PC\Administrator'.

what can be the error,please help.

[edit]Code block added - OriginalGriff[/edit]