This message usually means you mistyped the name of one of DPL's built in functions. The examples below cause this error.
@srqt(2.0) @Round(Profit, 2)
Remember that DPL is case sensitive (@Round is not the same as @round). It is good practice to use the Function button rather than entering function names by hand. The correct calls are
@sqrt(2.0) @round(Profit, 2)
Versions: DPL Professional, DPL Enterprise, DPL Portfolio