diff --git a/src/main/java/org/gcube/datatransfer/resolver/services/DataMinerResolver.java b/src/main/java/org/gcube/datatransfer/resolver/services/DataMinerResolver.java
index b095db5..e5a848d 100644
--- a/src/main/java/org/gcube/datatransfer/resolver/services/DataMinerResolver.java
+++ b/src/main/java/org/gcube/datatransfer/resolver/services/DataMinerResolver.java
@@ -80,7 +80,7 @@ public class DataMinerResolver {
 				//READ THE DATAMINER URL PORTLET FROM APPLICATION PROFRILE IN THE SCOPE fullScope
 				String dataminerEndPoint = "https://pre.d4science.org/group/prevre/dataminer-manager";
 
-				String queryString = "operatorId="+URLEncoder.encode(operatorId, UTF_8);
+				String queryString = "OperatorId="+URLEncoder.encode(operatorId, UTF_8);
 				if(req.getQueryString()!=null && !req.getQueryString().isEmpty()){
 					queryString+="&"+req.getQueryString();
 				}