Maybe your library has no reasonably binding ligands.

Did you use a positive control which is known to bind the target?

Hi Abel;

The library has been previously checked by someone else and she got good results.

I've had the same problem - did you find a solution?

Hi there;

finally I found the reason! I had lost my phages during binding of the phage target complex to my resins!

but dear Kate, you could also check the pH of your elution and neutralization buffer. Do not let the elution buffer to elute your phages for more than 10 minutes, because the phage infectivity decreases after this time! Be careful about that.

I'll be glad to hear about how you finally resolved this issue :)