I faced one Error while creating Purchase Order from Approved Purchase Requisition
System trade line number increment is not specified.
Purchase order creation has been cancelled due to errors
Reason: As mentioned in error message there is one parameter missing.'
Possible Solution:Click on “System Parameter” from infolog window or go to
System administration -> Setup -> System Parameter
Under System Line Number, Change the increment from 0 to 1.
Now try again to create PO.
Double click on purchase order number to open PO from.