Diagnosis
You are operating with a unit of measurement for calculatingvariable-size item quantity, whose dimension does not have an SI unitdefined for it.
Calculation of variable-size item quantity is carried out using SIunits, which are subsequently converted into the correspondingvariable-size item quantity units.
SI units must therefore be defined for the dimensions of the units ofmeasurement concerned. Exception: Dimensions that are 'withoutdimension'.

Procedure
Contact the person responsible for the units system, so that thisperson can define an SI unit for the corresponding dimension.