R help - Mar 2011 - apply function returning different results

For some reason when I apply a function to a single row in R it works, but
when that same row is in a data.frame it does not, see below:

apply(dx[954,], 1, query.db)
            2571
1092  0.06044147
3890  0.05948577
3273  0.05911261
794   0.05855583
4241  0.05854064
3560  0.05602690

apply(dx[954:955,], 1, query.db)
$`2571`
numeric(0)

$`1194`
         908         3754         5119         2835         3139
2775
 0.028935504  0.026941886  0.024762815  0.023335049  0.021892711
0.021001654
        1101         1762          401         3899         3727
4248
 0.020434257  0.020413724 -0.083333333  0.020111260  0.019872379
0.019840807
        3282         4585          798         5249          836
3570
 0.019729315  0.019524213  0.019440097  0.019410513  0.019288864
0.019052412
         726         3663         4775         3030         4938
3259
 0.018894556  0.018838258  0.018749506 -0.083333333  0.018416353
0.018240173
        1426         4563         3871          958         1242
1033


Here's the function code:

calc.enrichment <- function(cptdf){
    if(cptdf[4] %in% cptcodes[,1]){
        P.hit <- as.numeric(cptdf[6]) / sum.all.hits
        return (P.hit)
    } else{
        return (-miss)
    }

}

query.db <- function(dxdf){
    snquery = dbSendQuery(connection, paste("select distinct cpt4code from
DxRxLookup where icd9code = '", dxdf[4], "'", sep =
""))
    cptcodes <<- dbGetResult(snquery)

    #restrict this to constrain by Rx1 and Rx2 inputs
    h1 <<- which(cpt$Cpt %in% cptcodes[,1])
    y <<- which((cpt$Rx2 %in% dxdf[2] | cpt$Rx1 %in% dxdf[2]) &
(cpt$Rx1
%in% dxdf[3] | cpt$Rx2 %in% dxdf[3]))
    hits <<- intersect(y, h1)
    sum.all.hits <<- sum(cpt[hits,]$Log.Odds.Ratio)
    miss <<- 1 / (length(y) - length(hits))
    apply(cpt[y,], 1, calc.enrichment)
}

Thanks for any help!

	[[alternative HTML version deleted]]