ID:21165 Pin "<name>" has a pseudo-differential I/O standard, but does not have its complement pin. Because the output enable of the differential buffer is in use, the Fitter will not split the differential buffer to create a negative path without a complement output enable path.

CAUSE: A pseudo-differential output pin exists without its complement pin. Moreover, a differential buffer is used and the output enable of the buffer is in use. The Fitter will not split this differential buffer to create a complement pin path because the driver of the output enable of the complement buffer is unknown and the Fitter cannot duplicate the entire output enable path.

ACTION: Fix the design by either creating a complement pin for the pseudo-differential pin or using a true differential I/O standard.