"It's a big disappointment because this is the second time we've failed to get Hamann," said the Trotters boss. "I don't know why he's changed hisa mind - I haven't had an explanation.
"I would have liked Hamann because he could have done a job for us, but we haven't got him so we move on."
It is believed that Hamann's wife wasn't keen on the move to Bolton, preferring city life in Manchester instead.