RDKit Diversity Picker warning: the fingerprints in table 1 and 2 are not compatible, which may lead to wrong results

Hi RDKit lovers,

I'm trying to use RDKit Diversity Picker node in order to select a diverse set of molecules (set_1) that bias away from a second set of molecules (set_2). This second set of molecules is read from an SQL database where the fingerprints column is stored with a text format. After this second set is read the fingerprint column is re-casted to BitVector type using KNIME Create Bit Vector node.

When I use the RDKit Diversity Picker node with the set_2 molecules on the second input port the following warning is given by the node:

WARN: The fingerprints in table 1 and 2 are not compatible, which may lead to wrong results.

As far as I know the 2 fingerprints are of the same type and length. Can anybody tell why this warning message is triggered? Should I worry about it?

Thanks for any help,

Gio