When I was trying out the CIN 7 to ZOHO CRM connections, I always get an error saying "Invalid product code:". To give an insight on this, I am trying to put CIN 7's code (CODE/SKU) to ZOHO CRM's productCode field. Can you please tell me what's wrong about this?
Assuming that this error message is coming from a sales order link configured in your DSYNC account, this happens when you try to create an order in the destination system which has a line item with a product which does not exist.
You can either
a) configure a product link using DSYNC and synchronize products between the two systems (matching SKUs are crucial), or
b) do an export of products from one system and import into the other (outside of DSYNC)
In either case, you will have to have matching products in both systems.