The $PATH added to .bash_profile is not working after reboot

I am new to Ubuntu!
And I am trying to setup manually Maven by adding Maven directory into $PATH. I created .bash_profile file in my home directory. The file contains this:

export PATH=/opt/devel/tools/apache-maven-3.3.3/bin:$PATH

And then on a terminal, I run

source .bash_profile

Everything works fine and I can see the version after running mvn -version. But after rebooting laptop, running mvn gets the following error:

The program 'mvn' can be found in the following packages:
 * maven
 * maven2
Try: sudo apt-get install <selected package>

Could you tell me what I am missing please? Any help would be appropriate!

Edit 1
The output of echo $PATH is:

tuandang@Inspiron-N4030:~$ echo $PATH

/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games