"There was confusion about whether Cologne would let him trial for us and so he has gone back - that's all there is to it," says Alan Pardew, who is exploring his options.
Meanwhile, since the weekend's win, tickets are selling fast for Saturday's home fixture against Preston North End, who are just space and one point below the Hammers in the table.
Preston North End will be looking to take revenge for the 2-1 defeat on the opening day of the season.
Ticket prices for Saturday's match start from £22 for adults and £10 for non-member U16s; JHC members pay just £5.
Tickets are on sale now from the ticket office on 0870 112 2700.
Supporters are advised to book before closing time on Thursday with that being the last day for tickets to be posted.