Xls conversion

Hello,

I am trying to upload my xls file for conversion. However, every time I
try to upload the document I get the following error:
The name 'test survey_2014_05_06' is an invalid xml tag. Names must begin
with a letter, colon, or underscore, subsequent characters can include
numbers, dashes, and periods.

Is there a way to fix this?
Thank you,
Kathy