Lookup Transform error when linking using a DT_R8

I'm trying to lookup a value in another table linking on a column of datatype DT_R8. The lookup transform is complaining that I can't link on that datatype. However, the documentation says that it should work. I'm using the April CTP. Is this fixed in a later version? Any suggestions?

I'm sure DT_R8 does work in a Lookup. You may get an error such as -

[DDD, BackOfficeSoftwareKey]
One or more columns do not have supported data types, or their data types do not match.

This means that the source data type and the reference data type do not match. All lookups, the mappings between source and reference columns, must compare data types that match exactly, so you cannot compare a DT_I4 with a DT_R8 for example. One of them needs to be converted to the same type as the other before the match. You may be able to do this in the source extraction, or in the lookup reference table specification, use a SQL query with a CAST, or finally use a Data Conversion Tramsform or Derived Column.

|||I'm pretty sure that's not the problem becuase I've tried that approach. I've also double-checked the data types in the advanced editor and the datatypes do match. They are both DT_R8. It's not the usual error message that you mentioned. It's a different one that says "input column <column_name> has a datatype which cannot be joined on."|||DT_R8 is not allowed as a join column. So are DT_R4 and BLOBs (DT_TEXT, DT_NTEXT, DT_IMAGE).