I have a trigger that fires on Task after insert, update and delete.  The trigger calls a static method that passes in the trigger.new collection.

The trigger code runs fine if I'm editing just one Task record at a time, but if I use dataloader to update in bulk, then it doesn't process correctly.

Here is my method:

private static void doHoursCompletedHoursRemaining(List<Task> inNew)
    {
    	Set<Id> pmtlIds = new Set<Id>();
        for (Task t : inNew) {
        	String stringWhatId = '' + t.WhatId;
        	if (t.WhatId != null) {
        		if (stringWhatId.substring(0,3) == 'a0f') {
        			pmtlIds.add(t.WhatId);
        		}
        	}
        }
        
        //Gather all Data
        List<Project_Management_Task_List__c> lstPMTLs = new List<Project_Management_Task_List__c>([Select Id, Hours_Remaining__c, Actual_Hours_Completed__c, (Select Id, Hours_Completed__c, Hours_Remaining__c  From Tasks) From Project_Management_Task_List__c Where id in :pmtlIds]);
    	
    	if (lstPMTLs.size() > 0) {
    		Map<Id, Task> mapTask = new Map<Id, Task>([Select WhatId, Hours_Remaining__c, Hours_Completed__c From Task Where WhatId in :lstPMTLs]); 
    		
    		List<Project_Management_Task_List__c> PMTLsToUpdate = new List<Project_Management_Task_List__c>();
    		for (Project_Management_Task_List__c pmtl : lstPMTLs) {
    			Decimal Remaining = 0;
    			Decimal Completed = 0;
    			if (pmtl.Tasks.size() > 0) {
    				for (Task t : mapTask.values()) {
    					for (Integer i = 0; i < lstPMTLs.size(); i++) {
    						Remaining += mapTask.get(t.Id).Hours_Remaining__c;
    						Completed += mapTask.get(t.Id).Hours_Completed__c;
    					}
    				}
    			}
    			pmtl.Hours_Remaining__c = Remaining;
    			pmtl.Actual_Hours_Completed__c = Completed;
    			PMTLsToUpdate.add(pmtl);
    		}
    		update PMTLsToUpdate;
    	}
    }

All the code is doing is totaling the Hours Completed and Hours Remaining of all Tasks related to a specific Project Management Task List record. 

If I run in bulk, it totals all the tasks records and doesn't differentiate between different Project Management Task List records.  I was trying to use the WhatId as the key in the map and then use the containsKey method, but that didn't seem to work?

Thanks for any help.