> After seeing the message 'GDS Exception. 335544334. conversion error from
> string "DP"' I grepped my sources for a string DP, and there is none...
> Do you have an idea what could go wrong here?

The "DP" value is in the database, not in your sources, in a column that
is referenced in your query. Looks like your query treats the values in
the column as numbers or dates and Firebird fails to parse the "DP"
string and to convert it to the required type.

Roman