Issue with report in Excel format

I have created a custom report which has Order release number(123456-0001) and the order release line(0001) details in it. The value of order relese line is just 1 not 0001
when trying to pull the report in Excel format. But when it comes to PDF format its working fine (value for order release line is 0001).
Please help me to get the preceding 0s for the order release line(0001) in the Excel format.

Regards,
Shesmy