Filename rearrange

Applications Forms
#1

Hi Friends,

          I am using file upload in the form. Form Type(Single).

        Field type - > Filename

       i created the subfolder like.. "_group1_doc"

       Problem:  I generate the random number and put in filename before.. but the filename is not stored in the dic..

       i upload the filename "test.txt"
       Eg: _group1_doc (folder) inside "123_test.txt". Please help me..