strange issue in a report with formula field column

Hi All,

i have a custom report ,XML type 

it works well but when i change a code in a specified column  -formula column- 

it gives me an error and the report doesn't work after that ?

this is very strange problem

i don't understand why it occurs although i can generate the output correctly by the report builder environment

attached is the code before and after amendment

i need help ASAP pls

Thanks