i would like to change to a different tab when i click a button. my xaml is as follow:

<TabControl Name="Tabcontrol1" Margin="
5" SelectedIndex="0">
           
<TabItem Header="Properties" Opacity="1">
               
<Grid Width="1185" Height="945" Background="Snow"
>
</Grid>
</TabItem>
<TabItem Header="Others">
<Grid>
</Grid>
</TabItem>
</TabControl>
and my button click event:
    private void
BuildButton_Click(object sender, RoutedEventArgs e)
{
   
Tabcontrol1.SelectedIndex = "1";
}

is there something wrong? "Cannot implicitly convert type 'string' to 'int'" appears

thanks in advance