Have you tried recording a macro that does this and see what the differences
are?
I'm sure you've got lots of code  that you didn't include here.
Like: I don't see where you've saved wkbook, or RDate.
Also, if you're using Rows(1,1).delete
you don't need to do Rows(1,1).select...
Because, Rows(1,1).Delete is actually a combination of two commands:
Rows(1,1).Select
Selection.Delete
I'd start with recording the macro, and see if the recorded macro gives the same
result.
If it does not, compare the two and see how they differ...