You may sometimes be unable to place bids on a specific club's players.
Since our rules state that all trades must happen at fair market prices, we have an automatic system which keeps an eye on all bids in the game. This is to prevent clubs who know each other in real life from trading at special friend-prices or people with more than 1 club from transferring players and credits between their clubs.
If your bid is blocked by this system, it does not necessarily mean that you have conducted suspicious trades yourself. It may also be because a number of other clubs, who have logged in from the same network as you, have conducted too many trades recently. In any case, the cause is a number of coincidental logins and trades between clubs who have appeared on a network address which you have played Virtualmanager from recently. Examples of such networks include schools, work places and so on.
When your bid is blocked, you will need to find a different club to trade with.
On rare occasions, the block might be due to large mobile networks where all users share a common network address. When we are made aware of such occurrences, we add those networks to a list of addresses which which will not be affected by the automatic trade block.