relocate missing externals options

[Leo]

Hi,

I Speak English a Little.

I Use Version is 1.9

Step--

1. Windows tortoise svn client --> svn check out

2. right click on mouse -> tortoise svn -> relocate -> change URL (I select the Include externals.)

3. right click on mouse -> tortoise svn -> properties

4. disabled externals options. It isn't remove and edit. 

I want to enable externals options.

please the your answer.

thank you.

Leo.