I use Oligofectamine to transfect siRNA in 24 wells HeLa cells. In the application, I did some calculations and make a scale-up proportion. For example, it is suggested to dilute 3uL oligofectamine in 12uL Opti-MEM, while I mix 60uL oligofectamine in 240uL Opti-MEM and incubate for 5 minutes.
Once I performed this kind of mixture, I observed a big turbid white clump formed in the mixture (it looked alike fungus floating in media, you know. Please imagine

). Well, after 5 minutes incubation time, i re-suspend the mixture and mix with different siRNA. The transfection was not successful. No silencing was observed. This was repeated twice with same results. Alternatively, I have performed single mixture (3uL oligofectamine + 12uL Opti-MEM) for each and every reaction and they worked fine.
Does anybody have experience with this? I'm new to RNAi in my institute and nobody can be consulted