There are three potential reasons:

• Some banks require "corresponding" or intermediary banks to process wire transfers for them, and this often incurs additional costs which the intermediary banks deduct from the transferred amount^**
• You transferred the funds in a currency that required Walleteze to exchange on arrival - thereby incurring exchange fees and commissions plus possible rate flutuations
• You overlooked the Walleteze fee and/or the net amount estimate that was displayed on the deposit form

^** This issue primarily affects SWIFT transfers, but your bank will be able to clarify the situation and will offer you the option of paying the fees separately