Not Able to Increase InnoDB Buffer Pool Size in Mysql
Since the OS you are using is 64 bit, you need to make sure MySQL version you are using is 64 bit not 32 bit, how to get those information:

show variables like 'version_compile_machine';


If MySQL version is 32 bit then you will have results like

+-------------------------+-------+
| Variable_name           | Value |
+-------------------------+-------+
| version_compile_machine | i386  |
+-------------------------+-------+
1 row in set (0.00 sec)


Note MySQL 32 bit has limitation, you can not increase the memory to more than 1.8 to 2G.

If MySQl version is 64 bit then you will have the following results

    +-------------------------+---------+
    | Variable_name           | Value   |
    +-------------------------+---------+
    | version_compile_machine | x86_64  |
    +-------------------------+---------+
    1 row in set (0.00 sec)