Look Up Retail Product

Hi Experts,

im extending the app Look Up Retail Product, I have added my custom fields at RETAIL_ST_ARTICLE_INCL, but upon running the Look Up Retail Product Application it does not work anymore, if I delete the custom field the application works.

     this is the error it throws

core-min-0.js:85 2016-04-15 16:58:18 The following problem occurred: HTTP request failed500,Internal Server Error,{"error":{"code":"/IWBEP/MC_SB_DPC_USR/004","message":{"lang":"en","value":"RFC call ended with \"Communication Failure\" exception (The function call of RETAIL_ST_GET_PRODUCTS failed; a field may have been assigned to the parameter ET_PRODUCTS whose type is not compatible with this parameter)."},"innererror":{"transactionid":"2FE802E65792F1D580BC000AF77AFE6A","timestamp":"20160415085815.1260000","Error_Resolution":{"SAP_Transaction":"Run transaction /IWFND/ERROR_LOG on SAP NW Gateway hub system and search for entries with the timestamp above for more details","SAP_Note":"See SAP Note 1797736 for error analysis (https://service.sap.com/sap/support/notes/1797736)"},"errordetails":[{"code":"/IWBEP/CX_SD_GEN_DPC_TECH","message":"RFC call ended with \"Communication Failure\" exception (The function call of RETAIL_ST_GET_PRODUCTS failed; a field may have been assigned to the parameter ET_PRODUCTS whose type is not compatible with this parameter)","propertyref":"","severity":"error","target":""}]}}} -

     Hope you guys can help.