Well, from the PBP3 manual shows this for asm interrups which although doesn't specify DEFINE needs to be in caps they are all written that way.

6.2.2 DEFINEs
PBP offers a DEFINE to specify the name of the interrupt service routine label. The
label refers to the Assembly Language label that marks the beginning of your
service routine.
DEFINE INTHAND Label
For devices with multiple priority interrupts, PBP offers a single additional DEFINE
that allows you to specify a second label for a second service routine. This routine
will be used for low-priority interrupts.
DEFINE INTLHAND Label

And here it says they need to be in caps even a line that has the DEFINE RESET_ORG uses caps so I assume it needs caps.

2.3.2 Global DEFINEs
Other DEFINEs that are important, though less frequently used, are:
DEFINE NO_CLRWDT 1 'Don’t insert CLRWDTs
DEFINE LOADER_USED 1 'Bootloader is being used
DEFINE OSCCAL_1K 1 'Set OSCCAL for 1K PIC12
DEFINE OSCCAL_2K 1 'Set OSCCAL for 2K PIC12
DEFINE RESET_ORG 0h 'Change reset address for PIC18
DEFINE INTHAND Label 'Assign assembler interrupt
handler label
DEFINE INTLHAND Label 'Assign assembler low priority
interrupt handler label for
PIC18
See section 8.6 for a condensed list of DEFINEs with brief explanations.

2.3.3 DEFINEs defined
For the user familiar with Assembly Language, the major clue to understanding is
that DEFINEs in PBP are converted literally to Assembly Language #DEFINE
directives.
For the practical PBP user, there are a couple of fundamental points to consider:
1) DEFINEs are CASE SENSITIVE!
2) Specific DEFINEs are generally associated with PBP commands. The
command pages will describe how the relevant DEFINEs affect the
operation of each command.
DEFINEs are used by PBP to change the generated Assembly Language that
makes up the compiled program. A DEFINE might simply change an internal
register setting, or it might result in the use of an alternative Assembly Language
routine to accomplish a task.

For what it's worth I'm not an experienced programmer but If I'm wrong I'd like to know for future use. In the few prorams I've written I've always had to use caps for the defines to work but I haven't been calling asm routines. So I'd at least try it to see if it matters.

It appears this isn't the problem anyway. If I am wrong I apologize for any waste of time my conributions to this thread has accumulated.