Splitting A String With Split

I'm stumbling upon something I just can't figure out. I thought I was being very clever using the Split() function, and it did all work beautifully for a while.
I've got a list sort of like this:

Helloworld
Hello of World
Hello1 of Planet
And I want to be able to run the following code.

For Each u In units
d_type_a = Split(u.Value, " of")
Debug.Print (d_type_a(0))

Select Case u.Value
Case "Hello"
stuff...
Case "Helloworld"
stuff...
Case "Hello1"
stuff...
End select
next

But it fails on the Debug.print with a "Subscript out of range, nr 9" error. The debug is just there because it doesn't want to work. The debug.print DOES out put "Helloworld" into the Immediate window but then still fails which sorta confuses me.
The best I can figure out is that it just doesn't quite like the string without an " of" in it.