Hello Shlomi,
the value parser is exactly same as in BEx (as it is using BICS layer). Probably "+" is pointing to hierarchy, and this is making troubles.
you can try following:
* escape this "+" with "\+"
* select the variable manually and then use the function .getVariableExt() - this should bring the correct string, just place on some text box.
* if you have BEx, what would be the input string threre?
write short response, then I try to find such scenario inhouse and double check.