S10 brake lights

'98 S10 brake lights intermittent. CHMSL, both turn signals & emergency flashers work properly. Any suggestions?

Found a bad CHMSL relay (p/n 12088567) in the Relay/Fuse Center under the hood to be the cause. Odd label CHMSL (Center High-Mounted Stop Light) for this relay 'cause the CHMSL worked fine. It was the regular stop lights that weren't working. Go figure...........