bad gpg signature on src.rpm?

[Dave]

Hello,
	I've started signing rpms that i make with my gpg signature, this
has worked fine for stuff that i make. Tonight i downloaded an src.rpm made
by someone else in this case a centos 3rd party repo and recompiled it. I
did rpmbuild -ba --sign app.spec and gave my passphrase when prompted. The
rpm built successfully an exit code of 0. I su-d to root and tried an rpm
-Uvh app.spec as this is an upgrade not a fresh install and got the message
bad key with my keyid. I then ran as root rpm --import RPM-GPG-KEY-mine
which didn't return any errors and tried the upgrade again, same error. Any
suggestions?
	Thanks.
	Dave.