maybe you use a wrong deposit address . Did you check your deposit address a second time before you click deposit? you should always do that because you wouldnt know if you were infected by viruses and malware that auto paste a different address.

You should try to chat their costumer support and state your problems clearly in order to get some help .

Overall , forkdelta is a safe online exchange because it is also powered by etherdelta which is a well known exchange for tokens and altcoins.