Running Connected Query with Run Control Parameters using App Engine

Hello,

I created a connected query that has 1 parent query and 1 child query, and use this as DataSource for the report that I am going to generate.  I created an app engine that willl be called to generate this report.  However, I encounter this error  "Failed to create field instance for the field number 38, select number 1 (50,402)" and "Failed to read all query select definitions (50,389)" inside ValidateIfCurrent function.   what could be causing this error? Please adivse if I missed anything in the set up or creation of the connected query.

Thanks!

Janet