I have never used this yeast but reading about it not sure it is suppose to give off much banana...you might try a high fermenting temp to get banana...
Wyeast 3068 will get you awesome banana and clove favors for sure
I just bottled a hefe I brewed from a kit (Whiteley True Brew series Bavarian Hefeweizen) using WB-06. I noted a slight hint of banana in the aroma. But I didn't get any banana flavor in the little bit I tasted.
(Actually, I tasted a cider flavor - I've got another thread going on for that...)