Using space character in string value in windows registry

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registry

I have defined new extension(.abc) in windows registry by using following instructions:

[HKEY_CURRENT_USER\Software\Classes\abcApp_V1\shell\open\command]
@="D:\myDirecoty\abcApp.exe \"%1\""
[HKEY_CURRENT_USER\Software\Classes\.abc]
@="abcApp_V1"

This works properly and now each file with .abc extension opens the abcApp.exe program.

I have changed the Directory name to my Directory (add space between my & Directory):

@="D:\my Direcoty\abcApp.exe \"%1\""

It doesn't work! and the files with .abc extensions dont open abcApp.exe

What's the problem? Should I replace space with an special character?