Sorry in a hurry. What I try to say in the last sentense is that pre-block the membrane with normal sera from the SAME host species as the 2nd Ab. In another word if the 2nd Ab comes from rabbit then the normal sera from rabbit should be used to block the membrane. If 2nd Ab is made from horse then normal horse sera should be used to block the membrane. Or you can check their website at www.jacksonimmuno.com for more details.
Now I am waiting for the rabbit sera from Jacksonimmuno lab. Hopefully get some results on this weekend.
Did you try the rabbit serum as blocking solution?? I have the same problem with a rabbit anti-goat from dako, and I don't know what can I do!!!!