If you are passing a date range to your report, you must parse the data in a Conga Batch or Conga Trigger formula.

This article is provided for your usage but does not include support from Conga.

Formula Field Query:

“&Queryid=[Milestones]a0336000003solv?pv0=" + Id + "~pv1=" + TEXT(Start_Date__c) + "~pv2=" + TEXT(Completion_Date__c) +

Report Query:

"&ReportId=[Milestones]a0336000003solv?pv0=" + Id "~pv1=" + TEXT(MONTH(Start_Date__c)) +"/" + TEXT(DAY(Start_Date__c)) + "/" + TEXT(YEAR(Start_Date__c))