From BUDAT to Posting Date

Dear all,

I have an issue regarding converting BUDAT to FISCPER via ABAP code

Field Routine is as below

data: lv_string(7), lv_month(2), lv_year(4), lv_fper(7).

lv_month = SOURCE_FIELDS-BUDAT+4(2).
lv_year = SOURCE_FIELDS-BUDAT+0(4).

concatenate lv_month lv_year into lv_fper SEPARATED BY '.'.

concatenate '0' lv_fper into lv_string.
result = lv_string.

As attachment you can see a test reult of the specific code.

I wonder why the output is bringing irrelevant data.

Thanks.