(no subject)

Dear R
I'm trying to do a correlation matrix for some variables I have.
Unfortunately there are some NA entries for some of the variables 
I tried the following

cor(sleep[c("logbw", "logbrw", "SlowSleep", "ParaSleep", "loglife",
"loggest")])

but it told me
Error in cor(sleep[c("logbw", "logbrw", "SlowSleep", "ParaSleep", "loglife",
: 
        missing observations in cov/cor

How can I get R to conduct a correlation matrix for this data set??

brett