Error in .xts(e, .index(e1) in quantstrat - r

Question

I get an error when running my quantmod code:
´Error in .xts(e, .index(e1), .indexCLASS = indexClass(e1), .indexFORMAT = indexFormat(e1), :
index length must match number of observations´
My code (partly from http://rbresearch.wordpress.com/2013/02/19/momentum-in-r-part-4-with-quantstrat/) is:
# qstratRank.R
qstratRank <- function(symbols, init.equity=100000, top.N=1,
max.size=1000, max.levels=1) {
# The qstratRank function uses the quantstrat framework to backtest a
# ranking or relative strength strategy
#
# args
# symbols : character vector of symbols
# init.equity : initial equity
# top.N : trade the top N ranked assets
# max.size : maximum position size
# max.levels : maximum levels to scale in a trade
# max.size and max.levels are passed to addPosLimit
#
# return value
# returns a list: end.eq, returns, book, stats
# remove variables
suppressWarnings(rm("order_book.Rank", pos=.strategy))
suppressWarnings(rm("account.Rank", "portfolio.Rank", pos=.blotter))
suppressWarnings(rm("account.st", "port.st", "stock.str", "stratRank",
"initDate", "initEq", 'start_t', 'end_t'))
# set initial variables
initDate <- "1900-01-01"
initEq <- init.equity
port.st <- "Rank"
account.st <- "Rank"
# trade the top "N" ranked symbols
N <- top.N
# initialize quantstrat objects
initPortf(port.st, symbols=symbols, initDate=initDate)
initAcct(account.st, portfolios=port.st, initDate=initDate,initEq=initEq)
initOrders(portfolio=port.st, initDate=initDate)
# initialize a strategy object
stratRank <- strategy("Rank")
# there are two signals
# the first signal is when Rank is less than or equal to N
# (i.e. trades the #1 ranked symbol if N=1)
stratRank <- add.indicator(strategy=stratRank, name="SMA",
arguments=list(x = quote(Cl(mktdata)), n=50), label="SMA50")
stratRank <- add.signal(stratRank, name="sigComparison",
arguments=list(columns=c("Close", "SMA50"), relationship="gt"), label="Cl.gt.SMA50")
# the second signal is when Rank is greter than or equal to N
# (i.e. trades the #1 ranked symbol if N=1)
stratRank <- add.signal(strategy=stratRank, name="sigThreshold",
arguments=list(threshold=N, column="Rank",
relationship="gt", cross=FALSE),
label="Rank.gt.N")
# add buy rule
stratRank <- add.rule(strategy=stratRank, name='ruleSignal',
arguments = list(sigcol="Cl.gt.SMA50", sigval=TRUE,
orderqty=max.size, ordertype='market',
orderside='long', pricemethod='market',
replace=FALSE, osFUN=osMaxPos),
type='enter', path.dep=TRUE)
stratRank <- add.rule(strategy=stratRank, name='ruleSignal',
arguments = list(sigcol="Rank.lte.N", sigval=TRUE,
orderqty=max.size, ordertype='market',
orderside='long', pricemethod='market',
replace=FALSE, osFUN=osMaxPos),
type='enter', path.dep=TRUE)
# add exit rule
stratRank <- add.rule(strategy = stratRank, name='ruleSignal',
arguments = list(sigcol="Rank.gt.N", sigval=TRUE,
orderqty='all', ordertype='market',
orderside='long', pricemethod='market',
replace=FALSE),
type='exit', path.dep=TRUE)
#set max position size and levels
for(symbol in symbols){ addPosLimit(port.st, symbol, initDate, max.size, max.levels) }
print("setup completed")
# apply the strategy to the portfolio
start_t <- Sys.time()
out <- try(applyStrategy(strategy=stratRank, portfolios=port.st))
end_t <- Sys.time()
print(end_t-start_t)
# update Portfolio
start_t <- Sys.time()
updatePortf(Portfolio=port.st, Dates=paste('::', as.Date(Sys.time()), sep=''))
end_t <- Sys.time()
print("trade blotter portfolio update:")
print(end_t - start_t)
# update account
updateAcct(account.st)
# update ending equity
updateEndEq(account.st)
# get ending equity
eq <- getEndEq(account.st, Sys.Date()) + initEq
# view order book to confirm trades
order.book <- getOrderBook(port.st)
# get trade statistics
stats <- tradeStats(port.st)
# portfolio returns
ret1 <- PortfReturns(port.st)
ret1$total <- rowSums(ret1, na.rm=TRUE)
return(list(end.eq=eq, returns=ret1, book=order.book, stats=stats))
}
I then run:
bt <- qstratRank(symbols=symbols, init.equity=100000, top.N=2,
max.size=1000, max.levels=1)
The issue might be with my ´SMA50´ indicator, and signal and rule.
Any ideas?
Best Regards