Why my Scrollview not working?

I am kinda new to android application and I'm trying to develop and DataGrid with TableLayout and TableRow. Table Row has 5 TextViews and I want to scroll from one end to the other. TableLayout is in a ScrollView but not working.. I am pretty sure I might be missing a Code Line.. If anyone can, Please Help me Thanks in Advance.

My XML is written as follow

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.sfa_app_project.Invoice_activity" >

    <TextView
        android:id="@+id/lblInvoice"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="INVOICE"
        android:textSize="40sp" />

    <Button
        android:id="@+id/btnAddItem"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/lblInvoice"
        android:layout_marginTop="-5dp"
        android:layout_marginLeft="280dp"
        android:text="+"
        android:textSize="40sp" 
        android:onClick="btn_ClickAddItem"/>

    <Spinner
        android:id="@+id/spinItemList"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/lblInvoice"
        android:spinnerMode="dropdown"
        android:entries="@array/planets_array" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/spinItemList"
        android:id="@+id/lblqty"
        android:text="Quantity" />

    <EditText 
    android:inputType="number"
    android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/lblqty"
        android:layout_marginTop="20dp"
        android:id="@+id/txtqty" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtqty"
        android:layout_marginTop="20dp"
        android:id="@+id/lbldisc"
        android:text="Discount (%)" />

    <EditText 
    android:inputType="number"
    android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/lbldisc"
        android:layout_marginTop="20dp"
        android:id="@+id/txtdisc" />

     <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtdisc"
        android:layout_marginTop="20dp"
        android:id="@+id/lbldisclbl"
        android:text="Discount :" />

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtdisc"
        android:layout_toRightOf="@+id/lbldisclbl"
        android:layout_marginTop="20dp"
        android:layout_marginLeft="20dp"
        android:id="@+id/lbldiscamt"
        android:text="200.00" />

      <ScrollView
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:layout_below="@+id/lbldisclbl"
          android:layout_weight="1"
          android:scrollbars="horizontal|vertical" >

      <TableLayout
          android:id="@+id/grditemlist"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:fillViewport="true"
          android:orientation="vertical"
          android:scrollbarStyle="insideOverlay"
          android:scrollbars="horizontal" >

          <TableRow 
            android:layout_height="wrap_content"
            android:layout_width="match_parent">
              <TextView
                android:layout_width="160dp"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:id="@+id/lblItemlbl"
                android:text="Item" />              

              <TextView
                android:layout_width="80dp"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:id="@+id/lblQtylbl"
                android:text="Quantity" />

              <TextView
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:id="@+id/lblUPricelbl"
                android:text="UnitPrice" />

              <TextView
                android:layout_width="80dp"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:id="@+id/lblDiscAmtlbl"
                android:text="Discount (%)" />


              <TextView
                android:layout_width="120dp"
                android:layout_height="wrap_content"
                android:layout_marginTop="20dp"
                android:id="@+id/lblTotallbl"
                android:text="Total" />
          </TableRow>

      </TableLayout>
      </ScrollView>

</RelativeLayout>