Dynamic File Name as source file format

Hi Experts,

I have to load daily Excel Workbook to HANA.

Files will come to shared Folder in BODS Job Server in the format 'FILE_NAME_<DAYMONYYYY>'.xlsx format.

Everyday the file name will be appended with System Date Format.

Example: 'FILE_NAME_17JUL2014.xlsx', 'FILE_NAME_18AUG2014.xlsx' etc.

I tried to achieve it by creating a substitution parameter and using it to dynamically define file name.

But I am not able to define the parameter correctly. (screenshot attached).

Please advise where I am doing wrong.  Is there any better way to achieve it.

Thanks,