Cant sell any players !!!

Have just started a new game with Dortmund and would like to revamp my squad so transfer listed a number of players (Tinga, Valdez, Zidan, Rangelov ect.) Even when a offer them to clubs at half their value I still get no offers. I occasionally get a offer of loan to buy and every time the other team cancels their offer as they have set their sights on other targets, this has happens over and over again. It is virtually impossible for me to sell any players.

Any advice as I am very frustrated and getting a bit fed up