Just add the below code in lookup() of StringEdit control in Form to get the Business Unit Lookup:
public void lookup() { Query query; SysTableLookup sysTableLookup; super(); //DimAttributeOMBusinessUnit is a View sysTableLookup = SysTableLookup::newParameters(tableNum(DimAttributeOMBusinessUnit), this); sysTableLookup.addLookupfield(fieldNum(DimAttributeOMBusinessUnit, Value)); sysTableLookup.addLookupfield(fieldNum(DimAttributeOMBusinessUnit, Name)); query = new Query(); query.addDataSource(tableNum(DimAttributeOMBusinessUnit)); sysTableLookup.parmQuery(query); sysTableLookup.performFormLookup(); }