Air carrier pilot conducting a visual approach to SBY reported a glideslope deviation message even though they were properly aligned with the PAPI lights.

Narrative

We were cleared for a visual approach for Salisbury runway 32; utilizing the ILS procedure as a back up. Initially; the heading/course was wandering laterally and I reselected heading and manually steered the aircraft on centerline. Upon reaching the final approach fix; I reactivated approach mode. The course and glideslope captured appropriately. Shortly thereafter; the course began to deviate again. I de-selected auto pilot and continued to hand fly the approach. On the approach plate; it is noted that the PAPI lighting and electronic glideslope are coincident at 3°. However; while maintaining 2 white/2 red lights on the PAPI beginning at approximately 200 feet AGL; the electronic glideslope began to show a deviation in excess of 1.5 dots low. We received a glideslope deviation EICAS message. We continued visually maintaining the 2 white/2 red lighting. Landing was performed safely and without incident. We contacted tower upon landing to inquire of any other complaints or comments regarding deviations.Cause: Possible ground navigation issue.Suggestion: Recalibrate ILS/PAPI.