NSIS callback function crashes installer when file is not present -

I'm stuck on this. I have this callback function at the bottom of a subscript (.nsh) file. (As you can see that I am using LogicLib):

  Function InstallFoo Message Box MB_OK "Install $ {if} $ {FileExists}" $ EXEDIR \ Module \ foo.zip "Message Box MB_OK" foo.zip, within the InstallFoo function, install it! " Nsisunz :: "$ EXEDIR \ Module \ foo.zip" "$ INSTDIR \ Foo" $ {other} Message Box MB_OK "No Fujipas found." Do not do anything "$ {endf}" message box MBiOk "End access" functionand  

Everything works properly as I want when 'foo.zip' exists but When this is not, the installer crashes, and why can not I really understand

I hope that even when 'foo.zip' is not found, even then able to handle it It's not doing anything like that. Now what happens is that the installer crashes with "setup.exe" Instructions on "Some-Address" referenced memory in "some-other-address". Memory can not be "read".

Within sections in my script I have the same type And it works fine, whether zip files are present or not. It does not work in this callback function only, so I think there is something in it to do with the callback function.

'foo.zip file does not exist The '- in case I get the following messageBox: "" inside InstallFoo function "had no Fukjip. The first thing that can be called after callback function with the callback function is that callback was also called from, it has a message box printout.

Does anyone know about why I am wrong here?

< P> It seems that whenever I do nothing in the callback function, I get crashes.

Does it allocate some memory to the NSIS callback function, and if it is not used then we get crashes .. ?? strange.