Cannot Use Tooltip with Connection Map?

[andrew_gohgoh]

I'm trying to pass a description for my connections via the "Tooltip" field, but they keep getting rejected. My tooltip field is unique for each connection because it involves a concatenation of each origin and destination. 

I thought the issue might be the fact that my dataset has some connections that share the same address, so I created a new dataset where this was not the case (2nd image) and the issue remains.   

Real dataset w/ shared connections