Little problem with nsis

Hie all,

I'have one little problem, on my script i can't verify if a software is already installed. By example, i want to check if the computer already had MySQL whith this:

IfFileExists $HKEY_CURRENT_USER\Software\EMS\MySQL Manager
MessageBox MB_OK "Mysql is already installed"
return

ExecWait '"INSTDIR\Sql_Express.exe"'


But that don't word and say :
Could'nt resolve Manager in section MySql

Have a nice day

P.S. : Excuse my english, i'am french

You can not use IfFileExists to read from the registry

try:

!include LogicLib.nsh

ReadRegStr $0 HKCU "Software\EMS\MySQL Manager"

${IF} $0 != ""

  #do something

${EndIf}

Thank's for your help, that's good ^^.

Edit :
I have one other question. how the space is handle?

Because with space in my register directory make me one more argument.
Is it %20 like internet site adress?

Edit 2 :
I have find, i just have tu put my adress on " ".