Jennifer- skin is an excellent control for CD34 as the dermis is rich in
s0-called dendritic interstitial cells(undifferentiated fibroblasts) as well
as blood vessels. CD34 also stains most endothelium. As to your problem, try
another block of normal skin (normal, not a keloid as the CD34+ dendritic
fibroblasts in a keloid have all transformed into actin+ myofibroblasts).
Also, use Plus slides and nothing should wash off. Also, CD34 is usually
quite resistant to formalin fixation and Citrate antigen retrieval should be
unnecessary for CD34 (at least the QBend-10 clone that I use.)
Tonsil is known as the poor man's control for immuno's- there should be some
CD34+ fibroblasts just beneath the mucosa of a tonsil but not many. Hope
this helps.

Jeff Silverman