Peptide-KLH coupling HELP!!

[Jeffrey Andrew Mahr]

I am coupling a peptide to KLH using glutaraldehyde.  When I stop the
reaction using 1M glycine (in PBS), the solution turns yellow, as it
should - but then turns orange.   By the end of an hour it has turned
almost brown.  I have coupled this same peptide (same synthesis) to KLH
before and the solution stayed yellow.  Has anybody any light to shed on
this situation?  I have tried twice, checking my pH's in between, and
gotten the same result.
THanks, Jeff Mahr jmahr at emory.edu