Need BAPI to get the F4 values for a table field.

I tried executing the FM BAPI_HELPVALUES_GET with values:

OBJTYPE = BUS6030

METHOD = POST

PARAMETER = DOCUMENTHEADER

FIELD = COMP_CODE

where DOCUMENTHEADER is a structure

I get the 128 values for F4 of the the field

Now I execute the same FM with following values:

OBJTYPE = BUS6030

METHOD = POST

PARAMETER = ACCOUNTGL

FIELD = GL_ACCOUNT

where ACCOUNT GL is a TABLE.

I get some error.

I need a BAPI so get the f4 value for this field in the tab;e .

Thanks in advance

Rajiv Kanoroa