Xamarin Picker和Entry的问题

我是Xamarin 初学者，我在使用Xamarin 开发简单的APP时，页面上增加了一个Picker选择器，下面接着是一个Entry文本，在运行调试时发现先选择了Picker选择器内容后，再点Entry文本进去 修改值时一直重复要求选择Picker的值。

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
              xmlns:control="clr-namespace:TestApp.MyStyle"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:TestApp"             
             x:Class="TestApp.MainPage">


    <StackLayout  Margin="20">


        <TableView Intent="Settings" >
            <TableRoot>
                <TableSection Title="远程I0控制">
                    <ViewCell  >
                        <StackLayout Orientation="Horizontal"  >
                            <Label Text="站号选择"  VerticalOptions="Center" Margin="16,0,0,0"/>
                            <control:MyPickerRenderder Title="SlaveID"  HorizontalOptions="EndAndExpand"   TextColor="#f35e20" x:Name="SlaveList" SelectedIndexChanged="SlaveList_SelectedIndexChanged">
                                <control:MyPickerRenderder.Items>                                  
                                </control:MyPickerRenderder.Items>
                            </control:MyPickerRenderder>
                        </StackLayout>
                    </ViewCell>              

                    <ViewCell >
                        <StackLayout Orientation="Horizontal"  >
                            <Label Text="起始地址"  VerticalOptions="Center" Margin="16,0,0,0"/>
                            <control:MyEntryRender Keyboard="Numeric"   Text="0"   x:Name="StartAddress"    Placeholder="输入起始地址" TextColor="#f35e20"  HorizontalOptions="EndAndExpand"  HorizontalTextAlignment="End"    VerticalOptions="CenterAndExpand" />
                       
                        </StackLayout>
                    </ViewCell>
                    <SwitchCell Text="开启或关闭" On="true" OnChanged="SwitchCellChanged" />
                    <ViewCell>
                        <StackLayout Orientation="Horizontal" >
                            <Label Text="回读状态"  VerticalOptions="Center" Margin="16,0,0,0"/>
                            <Label Text="-" x:Name="status" HorizontalOptions="EndAndExpand"  VerticalOptions="Center" TextColor="#f35e20"/>
                        </StackLayout>
                    </ViewCell>
                </TableSection>
            </TableRoot>
        </TableView>
    </StackLayout>
</ContentPage>

请问各位朋友，怎么解决？