Modify Dropdownlist Target-Release

hi,

is there a way to "reduce" the dropdownlist of available target-releases in a alm workflow script?

i want to show only releases where the REL_END_DATE is greater than the current date an the parent folders name is "Build"...
the follwing code works fine to get the desired list of REL_ID, but i can't assign it to the field BG_TARGET_REL.

    com1.CommandText ="select REL_ID from RELEASES, RELEASE_FOLDERS where REL_END_DATE >= trunc(sysdate) and REL_PARENT_ID = RF_ID and RF_NAME = 'Build'"
    Set RelSet = com1.Execute

    RelList = ""
    For i = 0 To RelSet.RecordCount -1
        relId = RelSet.FieldValue(Cstr("REL_ID"))
        RelList = RelList & relId & ","
        RelSet.Next
    Next

    Bug_Fields("BG_TARGET_REL").List = RelList

the last statement leads to the following error-message:

Invalid procedure call or argument: 'Bug_Fields(...).List':
====================
==> Bug_Fields("BG_TARGET_REL").List = RelList
====================

thanks in advance,
adrian