StartWorkflowOnListItem Web Service Variables with Whitespaces

Hi,

i use Web Service to start Childworkflows like description in this Post. A Childworkflow (not designed from me) got some Starvariables like "Check in (Admin)" and i cant pass Start Data for these Columns. I tried to rename like this "_x0020_" for the whitespaces without success.

This work's

<Data>
<texta>example Text</texta>
</Data>

This doesnt work

<Data>
<text a>example Text</text a>
</Data>

Thanks in advanced