Substr from EC.<FieldName>

I am trying to extract first 4 characters from date. I created new custom field which is DOB and it is date type. I am using this {REPORT ENTITY DETAILS:[=’{EC.DOB}’.substr(0,4)]} but I am not getting any output. Same I used in [=’{DATE}’.substr(0,4)]} which is return today date.

Can anyone guide me to resolve this

That is not valid Report syntax. '{EC.DOB}' does not mean anything. That is Tag syntax, and EC.DOB is not a Tag.

Get a Report working with the full DOB, then post the Report here, along with the output.