Unable to add an image in template with excel output

Hi,

I got a warning when my concurrent are executed also i got the xml file in the output without format, but this only happen when i add alternative text in my template, because i dont know other way to add an image in an excel output.

this is the alternative text: src="url({'${OA_MEDIA}/ck.png'})"

this file is already uploaded in media folder, also i try with others files and i get the same error:

REP-0004: Warning: Unable to open user preference file.

could somebody explain me, why i got this warning? and if it's posible, how can be solved?