Couple points...
The ldf is not in the filegroup. Log files are not part of data filegroups.
The primary file (the mdf, file 1) cannot be emptied, there will always be data in there.
Why are you moving data back and forward across files? What's the goal here?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability