Fire Mage - Impact Bug - Not Spreading Dots

Fire Mage - Cata Classic - Issue with Talent in the Fire tree (Impact). It Reads. Gives your Damaging spells a 10% chance to reset the cooldown on fire blast and to cause the next fire blast you cast to stun the target for 2 sec and spread any fire damage over time effects to nearby enemy targets within 12 Yards.

I can’t get the Damage over time abilities to Spread. I have tested on Players in. In dungeons and on Target dummies. After playing fire for 2 days not once have i had impact cause my fire blast to spread Dots. This has to be a Bug. Not working as tooltip is reading at all.