Hi Anand,
you should preferentially use "NVARCHAR" instead of the non-unicode derivate "VARCHAR". As ABAP supports both unicode and non-unicode systems, we only allow the mapping of Strings/character literals from ABAP to NVARCHAR variables in HANA in all ABAP on HANA systems.
Please find an example of a _SYS_BIC procedure in an AMDP in class CL_EPM_OIA_SIMP_BP_CLSF_AMDPDT (method AMDP_GET_BP_CLASSIFICATION). Should be available in your system.
And you can additionally try to execute the call you put into the AMDP directly in the HANA SQL console.
Cheers,
Jasmin