Oracle Message PGA-20960 - missing string parameter, required when PGA_CAPABILITY=string

ERROR	missing string parameter, required when PGA_CAPABILITY=string
CAUSE	The PGA_CAPABILITY parameter specified , but another required parameter, , was omitted.
ACTION	Add the missing parameter to the gateway initialization file. Refer to Appendix A, Gateway Initialization Parameters, in the Oracle Database Gateway for APPC Installation and Configuration Guide for information on required parameters.