Peter-
Hey, thanks for your help!!! I got it!!! I needed to set all registers to zero, i.e., including S, R, T, and I. I should have remembered to check for that - your last suggestion reminded me to do that (I so far away from programming since I was younger). Again, thank you for taking the time, I greatly appreciate it!
See code below for tweak that works for me:
FMRR%:
L(N:L(F:L(M:L(W:L(MP:L(MF:L(S:L(R:L(T:L(I:0))))))))))_mult_
( IF(P/YR=0: L(P/YR: 1 ) : 0 )+
L(I: G(IRR%)_div_P/YR )+
L(S: SAF%_div_P/YR )+
L(R: RSK%_div_P/YR )+
_sum_( G: SIZEC($): 1: -1: L(C: FLOW($:G) )+ L(T: #T($:G) )+ L(X: G(M)_mult_SPPV(G(S):G(T))+ G(C)_mult_USPV(G(S):G(T)) )+ L(MP: G(MP)_mult_SPPV(G(S):G(T)) )+
IF(G(C)<=0: L(MP: G(MP)+ G(C)_mult_(G(S):G(T)) )+ L(M: G(X) ) : L(MF: G(MF)+ SPFV(G(R):G(N))_mult_ G(C)_mult_USFV(G(R):G(T)) )+ IF(G(M)+G(C)>0: L(W: G(W)+ SPFV(G(R):G(N))_mult_ ( G(M)+ G(C)_mult_USFV(G(R):G(T)) ) )+ L(M: G(X) ) : IF(G(X)<=0: L(M: G(X) ) : L(P: IP( LN( -G(M)_mult_G(S)_div_100_div_G(C)+1 )_div_ LN( 1+G(S)_div_100 ) ) )+ L(W: G(W)+ SPFV(G(R):G(N)+G(P))_mult_ ( G(C)_mult_USFV(G(R):G(T)-G(P))+ G(M)_mult_SPPV(G(S):G(P))+ G(C)_mult_USPV(G(S):G(P)) ) )+ L(M: 0 ) ) ) )+ L(F: G(F)+ G(C)_mult_ USFV(G(I):G(T))_mult_ SPFV(G(I):G(N)) )+ L(N: G(N)+G(T) ) ) )+
IF(S($IN): $IN-G(M)-FLOW($:0) : IF(S($OUT) OR S(P/YR): $OUT-G(W) : IF(S(FMR%) OR S(SAF%) OR S(RSK%): (G(M)+FLOW($:0))_mult_ SPFV(FMR%_div_P/YR:G(N))+ G(W)+ 0_mult_(SAF%+RSK%) : IF(S(MIR%): FLOW($:0)+ G(MP)+ G(MF)_mult_SPPV(MIR%_div_P/YR:G(N)) : FLOW($:0)_mult_ SPFV(IRR%_div_P/YR:G(N))+ G(F) ) ) ) )