Need to specify L01 instead of L1 in a macro

We use zen 2010 with our microscopes, and it includes some pre built macros, including one for a multiple point time series setup. The system struggles saving the large amount of data produced, and often freezes, so I am creating a macro in imageJ to sort the time series from the temporary folders as a backup system, however I have run into a hitch:

Using the import->time series option,
Need to specify the location code from the program as
L01, L02, L03 etc.
Have been using this line;
Loci = "L0" + i
Where i is the the counter in a for loop
The problem is I get "L1" instead of "L01"

Is there an alternative to '+' which keeps it as just a text string?