Most of the affiliate programs have minimum limits for transferring to affiliate accounts. Are you sure that the balance they owe you is in every case above the specified limit?
I always receive commissions from Vegas Affiliates and Gambling Wages. I don't recommend you to promote Casino Paycheck, Prism Casino, FirstGrand. Also you should know that all casinos of Gambling Wages are listed in the rogue list of CasinoMeister. I liked this program, but due to their casinos' reputation I can't promote them as I want.
Problem with Gambling Wages solved. They already transfer all to WU, but send message via internal mail service in affiliate program (not by e-mail), so I did not saw that message.
lol