issue with xts affectin Return.calculate in PerformanceAnalytics

I came across the issue below trying to calculate simple returns of an xts object using Return.calculate() in PerformanceAnalytics. This returns a series of all zeros. The root of the problem, however, seems to be with xts for which division seems to be a challenge. What am I missing? Coercion to numeric is not really a reasonable solution.

p <- to.monthly(as.xts(s.ts), OHLC = FALSE)
head(aap)

? ? ? ? ? ? ? ? ? s1 ? ? ? ? ? s2
Dec 1999 ? ? ?1000.00 ? ? ?1000.00
Jan 2000 ? ? ?1021.27 ? ? ? 959.85
Feb 2000 ? ? ?1017.30 ? ? ? 962.06
Mar 2000 ? ? ?1022.99 ? ? ?1008.44
Apr 2000 ? ? ?1015.95 ? ? ? 980.95
May 2000 ? ? ?1044.30 ? ? ? 963.79

r <- Return.calculate(aap, method = "simple")
head(r)

? ? ? ? ? ? ? ? ? s1 ? ? ? ? ? s2
Dec 1999 ? ? ? ? ? ?0 ? ? ? ? ? ?0
Jan 2000 ? ? ? ? ? ?0 ? ? ? ? ? ?0
Feb 2000 ? ? ? ? ? ?0 ? ? ? ? ? ?0
Mar 2000 ? ? ? ? ? ?0 ? ? ? ? ? ?0
Apr 2000 ? ? ? ? ? ?0 ? ? ? ? ? ?0
May 2000 ? ? ? ? ? ?0 ? ? ? ? ? ?0

lr <- Return.calculate(aap, method = "compound")
head(lr)

? ? ? ? ? ? ? ? ? ? ? ?s1 ? ? ? ? ? ? ? ?s2
Dec 1999 ? ? ? ? ? ? ? ?NA ? ? ? ? ? ? ? ?NA
Jan 2000 ?0.02104695084364 -0.04097825672856
Feb 2000 -0.00389489202608 ?0.00229979652957
Mar 2000 ?0.00557765293308 ?0.04708304254280
Apr 2000 -0.00690557640376 -0.02763837145911
May 2000 ?0.02752266915648 -0.01764806131103

p[2]/p[1]-1

Data:
numeric(0)

Index:
NULL

as.numeric(p[2])/as.numeric(p[1])-1

[1] ?0.02127 -0.04015