Fstab after reboot does not work

I have a problem with the mount Windows directory.

1. (terminal) I mount:

   mount.cifs //192.168.1.151/_wymiana /mnt/share_2 -o user=wega

   and it works.

2. When I go to /etc/fstab and add:

   //192.168.1.151/_wymiana /mnt/share_2 cifscredentials=/root/.smbcredential_2,iocharset=utf8,sec=ntlm 0 0

After reboot it did not work:

.smbcredential_2 fileusername=wega   password=1234