app.path doesnt work

hello
this is my code
i try to open arcview programm but it isnt work

dim native as string
native=app.path
ret-shell("c:\\arcgis\arcexe83\bin\arcmap.exe "
& native " \\test.mxd",vbNormalFocus")

when i write instead of native :"c:\temp\test.mxd" is work
what not good in my code??/
thanks
oren t
tel aviv

VB Code:

dim native as string
native=app.path
ret-shell("c:\arcgis\arcexe83\bin\arcmap.exe "
& native  [b]&[/b] "\test.mxd",vbNormalFocus")

or

VB Code:

dim native as string
native=app.path
ret-shell("c:\\arcgis\arcexe83\bin\arcmap.exe "
& "[b]..[/b]\test.mxd",vbNormalFocus")

Would work as well