I need to add a line to SPLPROT. How?

[temnix]

I have a spell which is not supposed to work on creatures with any amount of resistance to cold. On top of those effects sits Protection from spell, opcode 318, but I need to add a custom line for protection from cold (stat 15) > 0. I try this code but get wrong results:

COPY_EXISTING    ~SPLPROT.2DA~    override    COUNT_2DA_ROWS 4 newrow BUT_ONLY
APPEND ~SPLPROT.2DA~ ~%newrow% 15 0 3~ OUTER_SET newrow = newrow + 1

Weidu is not my specialty. Either I'm doing something wrong here or a bit of code higher up in the tp2 is to blame. It is used for another spell and reads:

COPY_EXISTING    ~SPLPROT.2DA~    override    COUNT_2DA_ROWS 4 row    BUT_ONLY
APPEND ~SPLPROT.2DA~ ~%row% 15 50 2~    OUTER_SET    one = row + 1
APPEND ~SPLPROT.2DA~ ~%one% 15 127 3~    OUTER_SET    two = one + 1
APPEND ~SPLPROT.2DA~ ~%two% 260 %row% %one%~

I don't know why this code would cause problems for what goes below, but the spell in question instead of a new row gets pointed to the created "cold resistance > 127." Help would be appreciated. I'll credit you in the mod this is for when it comes out.