RFC Lookup in SAP PI 7.4

Hello there,

My interface is using a RFC Lookup in the graphical mapping and it is passing as input parameter an IDOC, the RFC in ECC is calling a abap class to create the entire mapping as per target system request for this interface, so the RFC exports the target xml, below the messaging mapping:

And this is the definition of the RFC in ECC:

However when I am testing the mapping I am not able to get any results from RFC, always get an empty result, my question is somebody knows how do I need to handle the data type for the Input and Output parameter in the RFC? Should be string? or what other data type I need to use in order I can pass though the xml correctly from PI into the RFC?...

Thanks.

Erika Juarez.