Operand type clash: int is incompatible with datetime2

The code below generates this error: ###### ERROR > Msg 206, Level 16, State 2, Procedure usp_TRAC_PSE_Step_12_Resource_Request_OBJECT-Production-Part1, Line 93 Operand type clash: int is incompatible with datetime2 ###### CODE insert into [dbo].[pse__Resource_Request__c_LOAD] (OwnerId, pse__End_Date__c, pse__Milestone__c, pse__Percent_Allocated__c, pse__Planned_Bill_Rate__c, pse__Practice__c, pse__Project__c, pse__Region__c, pse__SOW_Hours__c, pse__Request_Priority__c, pse__Resource_Request_Name__c, pse__Resource_Role__c, pse__Start_Date__c, pse__Status__c, Partner_Requested__c, OA_Migration_ID__c, CurrencyIsoCode, Percent_Onsite__c) select (select [OwnerId] from [dbo].[pse__Proj__c_LOAD] where [OA_Migration_ID__c] = p.id) 'OwnerId' , case when case when p.custom_35 is null then ISNULL(b.startdate, '01/01/1900 23:59:59.999') + 180 else p.custom_35 end 'SOW Hours' and isnull(b.deleted,0) 1 --and mp.stage = 'Active'