We had contact other networks, they replied us and said we can't promote on their networks because we promote through cb.
hmmm yeah, tanaka's comments confuse me a bit too ... anyway, yes, it's perfectly fine dependent on the rules of the program you join, but yes, you could for example have a sales page selling a CB product but also with links to some cheaper amazon products or such, as long as they are all in the same niche it makes sense, although it may give the buyer less likely to buy (more distractions etc) ...
Not sure what Tanaka is talking about, i use about 20 different ad/affiliate networks and none of them have problems with clickbank, unless they specifically state you can't sell CB products it is fine.
From another affiliate network's standpoint CB is just a transaction handler, however being accepted does depend on the quality of the product, the site design and the vendor..... PRODUCT - A lot of other affiliate networks won't do ebooks but if you sell software or some type of membership access they are more likely to accept you. SITE DESIGN - CB "sales page" sites are not as attractive to affiliate networks. They look for short sales pages with web form above the fold. VENDOR - Many networks peform business credit checks and a lot of CB vendors are small sole properietors that may or may not pass a credit check that requires bank and other media references. They will pass if they believe there is a chance they won't get paid. I hope that helps.