Importing values into Multiselect field fails

I am wondering what am I doing wrong?

I am stuck in migrating our data from our current CRM.
My current tusk is to create several custom Multiselect fields and populate them with our data.
As a test, I created a dummy Multiselect Field for a test Contact.
I used one of the generic Lists that pop by default.
Then I selected several values from that list and saved.
Next I exported the test Contact to see how the future import file should be formatted.
Next, I erased the values in the dummy Multiselect Field of my test Contact and saved.
Then I tried to import the exported file ( created by the SuiteCRM ) as a test to see if my previously manually entered data will be duplicated.
This is when the import failed.

This is the error ( it said Warning, but am pretty sure it is an error as the import did not happen) I got:
WARNING: [2] Declaration of SugarFieldMultienum::displayFromFunc($displayType, $parentFieldArray, $vardef, $displayParams, $tabindex) should be compatible with SugarFieldEnum::displayFromFunc($displayType, $parentFieldArray, $vardef, $displayParams, $tabindex = 0) on line 42 in file /var/www/html/MyNewCRM/include/SugarFields/Fields/Multienum/SugarFieldMultienum.php

Any ideas what went wrong here?