[Histonet] congo red on frozen sections?

[Monfils, Paul]

I was asked to do a congo red for amyloid on a mouse brain that had been formalin fixed, sucrose infiltrated, and frozen.  The researcher was certain that this brain would have a high level of amyloid.  I used a positive control that was human  tissue, formalin fixed, paraffin embedded.  The control slide stained perfectly.  The mouse brain shows absolutely nothing. Has anyone successfully done congo red staining on frozen sections?  Do you see any other possible problems in what I described?