In the statement,
Set ILoadCombinations = IModel.GetLoadCombinations(eComboType)
The variable eComboType should be assigned the appropriate value. The IModel.GetLoadCombinations method description in the RAM DA Developer's Guide shows that this input argument is the COMBO_MATERIAL_TYPE enumerator. ANALYSIS_CUSTOM will get you the Frame Analysis combos. Search for COMBO_MATERIAL_TYPE in manual to see the complete list of values.
Set ILoadCombinations = IModel.GetLoadCombinations(eComboType)
The variable eComboType should be assigned the appropriate value. The IModel.GetLoadCombinations method description in the RAM DA Developer's Guide shows that this input argument is the COMBO_MATERIAL_TYPE enumerator. ANALYSIS_CUSTOM will get you the Frame Analysis combos. Search for COMBO_MATERIAL_TYPE in manual to see the complete list of values.