Error when try to validate match invoice Payable R12.1.3 foreign currency

Error when try to validate invoice Payable R12.1.3 

APP-SQLAP-10000: ORA-01400 Cannot Insert NULL into ("AP"."AP_DISTRIBUTIONS_ALL"."DIST_CODE_COMBINATION_ID") occurred in
AP_APPROVAL_MATCHED_PKG.Exec_Matched_variance_checks<-AP_APP ROVAL-PKG.generate_Distributions<-AP_APPROVAL_PKG.APPROVAL<-APXINWKP
with parameter (invoice_id=112247 , Sys Xrate Gain Ccid=, Sys Xrate loss Ccid = )

while performing the following operation:
CALCULATE-VARIANCES-variance exists