[CentOS] sysctl errors

I get these errors from the following settings in /etc/sysctl.conf file:

# Custom Settings: net.ipv4.tcp_max_syn_backlog=2048 net.ipv4.tcp_fin_timeout=30 net.ipv4.tcp_keepalive_intvl=10 net.ipv4.tcp_keepalive_probes=7 net.ipv4.tcp_keepalive_time=1800 net.ipv4.tcp_max_tw_buckets=360000 net.ipv4.tcp_synack_retries=3 net.ipv4.tcp_rmem="4096 87380 16777216" net.ipv4.tcp_wmem="4096 87380 16777216" net.ipv4.tcp_mem="8388608 8388608 8388608"

---------errors-----------

# sysctl -p [errors] error: unknown error 22 setting key 'net.ipv4.tcp_rmem' error: unknown error 22 setting key 'net.ipv4.tcp_wmem' error: unknown error 22 setting key 'net.ipv4.tcp_mem'

any advice?