Adding 3rd unit... 3 unit battles

[AKDoc]

So I unlocked the ability to put in a 3rd unit. However whenever I try I can not as it says insufficient cost no matter how low of unit cost?! Yet I see screenshots of others able to put 3 2.0 units in the slot of similar level. Any suggestions? Anyone else have this problem? Whats the trick?
:?

[Keychain]

They increase their cost first by either using CP or a Library.

[AKDoc]

They increase their cost first by either using CP or a Library.

That makes little sense that to be able to open up the 3rd row it takes one set of upgrades, then weeks worth of upgrading to get a library to actually use the slot.

[Keychain]

Weeks? The Hero Statue takes a massive amount of resources but I don't think it'd take weeks. Especially for those that use CP.
But I agree that we unlock the rear slot quite easily only to find out we can't add a 3rd monster to the lineup for a while.

[grenadedodger]

Actually weeks is probably not too far from the mark if you're doing other stuff at the same time, it takes over a 100k in some resources to go from 6-7 on the statue and takes over 20 hours.

[DeathMan]

Actually weeks is probably not too far from the mark if you're doing other stuff at the same time, it takes over a 100k in some resources to go from 6-7 on the statue and takes over 20 hours.

Ouch! I better get some more warehouses built then...

[zerosum]

That makes little sense that to be able to open up the 3rd row it takes one set of upgrades, then weeks worth of upgrading to get a library to actually use the slot.

It make$ perfect $en$e. They are counting on lot$ of people who open that third $lot to $ay "crap, I gue$$ I'll $pend $ome money to increa$e my co$t $o I can u$e that third $lot".

[Exovian]

well, I buy the cost for a month now I can put goblin fighter2.5 lizardmanLancer2.5 and Goblin archer 1.5 together and the cost bonus become red color

anyway it was very impressive to have them because only level 5 and 100 count each can take over level 3 land