[CentOS] resize lvm

I have a laptop that I put centos 7 on and I started out with a 30gig partition.  I resized the other part of the disk to allow more space for centos.  I then created an unformated partition in the available space,  ran


pvcreate /dev/sda4



vgextend lvname /dev/sda4



lvextend -L 184.46G /dev/lvname/root


but when I run:



sudo resize2fs /dev/lvname/root


I get:



resize2fs: Bad magic number in super-block while trying to open /dev/lvname/root
Couldn't find valid filesystem superblock.


How do I resize the volume?



Thanks,



-wes