[Histonet] Staining FFPE with biotinylated SNA - how to block?

[M.O.]

Hello Histonet!

I ran a trial on FFPE mouse samples with a biotinylated lectin, SNA from
vector.  The SNA is Biotinylated Sambucus Nigra Lectin (Elderberry).  I
have never stained with anything like this, so I ran a test.

I deparaffinized, blocked with NGS, incubated overnight at 4C with the
diluted biotinylated SNA.  On the second day, I used Vector's ABC kit and
alkaline phosphatase (red) kit.

Once stained, I noticed a lot of background.  After looking into the
blocking step, would a biotin/avidin blocking step be the correct step
instead of a serum because I don't have a secondary?  How do I know what
needs to be blocked - biotin, avidin or both?  Is there a way to do this
without a kit and use solutions I may have in my lab?

Thank you for your help!

Sincerely,
Merissa