Hey Arya,
Yes you are right. Search helps can be case sensitive at times.
I will advise you better have good look at search help definition and database definition.
For example, You look at KNA1-NAME1 where lowercase is allowed, But if you look better at elementary search help DEBIA, it actually uses field KNA1-MCOD1 where lowercase is not allowed. This field is automatically filled by SAP program from KNA1-NAME1.
But, its not happening in other's case, i mean, in case of PBL's Serach Help of OIFB! User must to enter the case as per the data saved in data base, else no results
Regards,
Nikhil Ghadge.