In making trades involving blind bid dollars and players, if the transfer of players increases a teams salary space, the system doesn't allow that difference to be traded in the blind bid.
Team 1 ($5 cap space)
Player A $20, Player B $30, $30 blind bid
Team 2 ($60 cap space)
Player C $10
This trade won't be allowed because team 1 only has $5, although, after the trade he'll have $40 more because of the transfer of players. The only way to do this is to do 2 separate trades.