CustomApp Installation with CustomDoctype

Hi Guys,

I tried to install customapp with customdoctype ,but its giving some errors.

ImportError: Module import failed for Pre Purchase Order (frappe.core.doctype.pre_purchase_order.pre_purchase_order Error: No module named pre_purchase_order.pre_purchase_order)

please anyone can give me suggestions…

ERPNext cannot find any files for Pre Purchase Order. Investigate why that is the case