We had faced some issues in POS data loading through flat files , some of them I am listed here.
1. Make sure that you have access to flat files placed in ‘Inbound’ folder
Just click on files -> goto properties -> Security and check the security wheather you have read access or write access etc
2. Data seperator issue : Goto your flat file and open with notepad to see the seperator maintained in your flat files ( Assume that file is showing comma as seperator)
Make sure that same seperator used at Data source level and Info package level in the DSiM system
Goto RSA1-> choose your PC file (DSIM myself system) as your source, it will display /DDF data source list
Ex : /DDF/LOCATION_ATTR
choose your data source , in the extraction tab , fill comma in Data seperator field, same way you need to update at info package level