动态布局位置无效 求高手

我想工具条保持在底部（必须要动态加载进去，用include就不要说了 ）MailActivity.java
  
RelativeLayout rlToolbarLayout = (RelativeLayout)LayoutInflater.from(con).inflate(R.layout.web_toolbar, null);

rlToolbarLayout.setVerticalGravity(Gravity.BOTTOM);//  这两个都不可以
rlToolbarLayout.offsetTopAndBottom(R.id.web_webview);//这两个都不可以

LayoutParams lParams=new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT);

this.addContentView(rlToolbarLayout,lParams);

web_toolbar.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@id/web_toolbar_rl_layout"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="#EE000000"
    android:gravity="center_horizontal"
    android:padding="4dip"
    android:layout_gravity="bottom" >
    <ImageView
        android:id="@id/web_toolbar_iv_return"
        android:layout_width="38dip"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_marginLeft="15dip"
        android:layout_marginRight="15dip"
        android:src="@drawable/web_toolbar_return" >
    </ImageView>    <ImageView
        android:id="@id/web_toolbar_iv_refresh"
        android:layout_width="38dip"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dip"
        android:layout_marginRight="15dip"
        android:layout_toRightOf="@id/web_toolbar_iv_return"
        android:src="@drawable/web_toolbar_refresh" >
    </ImageView>    <ImageView
        android:id="@id/web_toolbar_iv_prev_page"
        android:layout_width="38dip"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dip"
        android:layout_marginRight="15dip"
        android:layout_toRightOf="@id/web_toolbar_iv_refresh"
        android:src="@drawable/web_toolbar_prev_page" >
    </ImageView>    <ImageView
        android:id="@id/web_toolbar_iv_next_page"
        android:layout_width="38dip"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dip"
        android:layout_marginRight="15dip"
        android:layout_toRightOf="@id/web_toolbar_iv_prev_page"
        android:src="@drawable/web_toolbar_next_page" >
    </ImageView></RelativeLayout>
mian.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="bottom"
    android:orientation="vertical" >    <RelativeLayout
        android:id="@+id/title"
        android:layout_width="fill_parent"
        android:layout_height="44dip"
        android:layout_alignParentTop="true"
        android:background="@drawable/wcity_title"
        android:orientation="vertical" >        <TextView
            android:id="@id/txt_city_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="60dip"
            android:layout_marginTop="10dip"
            android:text="福州"
            android:textColor="@color/white"
            android:textSize="18sp" />
    </RelativeLayout>    <WebView
        android:id="@id/web_webview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_below="@id/title"
        android:scrollbarSize="0dip" >
    </WebView>    <LinearLayout
        android:id="@id/web_pb_layout"
        android:layout_width="fill_parent"
        android:layout_height="25dip"
        android:layout_below="@id/title"
        android:background="#EE21185A"
        android:gravity="center"
        android:orientation="horizontal"
        android:visibility="gone" >        <ProgressBar
            android:id="@+id/pb_webview"
            style="?android:attr/progressBarStyleSmall"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center" />
    </LinearLayout></RelativeLayout>