Using Delphi 6 and IBO 4 I have experienced a problem implementing
DML caching and any help would be much appreciated.

The query is an IB_Query component and it is within an application
which works fine. The table is a simple table and the primary key
comprises 2 fields (both of type Int64).

My understaanding is that to implement caching with the scope of a
user's context is as simple as setting the DML caching flags on the
relevant datasets. Setting the datasets DML flag to announce inserts
causes an error when the dataset is posted. The error is "Invalid
variant type conversion". One of the keys is provided by a generator
so I image its value may only be known on the server.