[CentOS] hplip problems - configure: error: "cannot find libjpeg support"

I'm trying to get hplip-2.7.12 installed, and I'm reasonably sure that I had it installed on this box before my problems last month. Anyway, it will not build at the moment. It stops the Configure with "configure: error: "cannot find libjpeg support". However,

Package libjpeg - 6b-37.i386 is already installed.

Similarly, attempting to install hplip-3.9.2 stops with

warning: Missing REQUIRED dependency: libusb

but

Package libusb - 0.1.12-5.1.i386 is already installed.

Version 2.7.12 is the earliest version to support my printer. I'm fairly sure I had it installed on this box before my problems last month, and I'm fairly sure that it also was installed on FC6 some time back. Either of these versions would be fine.

Any ideas?

Anne