Hi,
    I am getting the following issue when launching the flow from the process. My requirement is to update the parent object when all the related childs are pass the criteria defined. I have Fund_Request__c is my parent object i want to update the status__c ='paid' when all the child records Payment_Status ='Paid'. Fund_Claim__c is my chld object is having Payment_Status__c picklist field.
I want to update the parent field when any child updated then i need to loop the all childs related to that parent.
Can any one help me to resolve this issue.
Error:The flow failed to access the value for eachFundClaim.Payment_Status__c because it hasn't been set or assigned.
My flow logic:

Variables:
1.falseCounter: type: Number : Default:0
2.trueCounter:type:Number:default:0 
3.RequestId:type:Text(collecting the parentid from the pb).
SobjectVariable:
1.eachFundClaim :Input/output type: Object:Fund_Claim__c(Child)
Sobject Collection Variable: 
1.relatedFundClaims:input/output type:Object:Fund_Request__c(Parent)
Fast Lookup:
Look up : Fund_Claim__c
Field: FundRequest__c equals {!RequestId}
Variable: {!relatedFundClaims}
Loop:
Loop through :{!relatedFundClaims}
loop variable: {!eachFundClaim}
Decision: Name True Condition:
Resource: {!eachFundClaim.Payment_Status__c } equals {!GlobalConstant.True}
Assignment: variable:{!trueCounter} operator add value:1(I would like to add this counter for each loop element when it payment_status__c is checked)
Assignment: variable:{!falseCounter} operator add value:1
Decision: Resource: {!falseCounter} operator less than value 1
Record update:
Update : Fund_Request__c (Parent Object)
Field: Id equals {!RequestId} criteria
field : Status__c equals Paid
The following is the mail i received about the flow failure
low Details
Flow Name: MDF_Update_Process
Type: Record Change Process
Version: 12
Status: Active

Flow Interview Details
Interview Label: MDF_Update_Process-12_InterviewLabel
Current User: Mohan kumar (0057F000001kHT3)
Start time: 4/22/2018 8:24 AM
Duration: 0 seconds

How the Interview Started
Mohan kumar (0057F000001kHT3) started the flow interview.
Some of this flow's variables were set when the interview started.
myVariable_old = a067F000006ZZEoQAO
myVariable_current = a067F000006ZZEoQAO

ASSIGNMENT: myVariable_waitStartTimeAssignment
{!myVariable_waitStartTimeVariable} Equals {!Flow.CurrentDateTime}
Result
{!myVariable_waitStartTimeVariable} = "4/22/2018 8:24 AM"

DECISION: isChangedDecision2_myRule_1_Payment_Status_c
Executed this outcome: isChangedRule_2_myRule_1_Payment_Status_c
Outcome conditions: and
1. {!myVariable_old} (a067F000006ZZEoQAO) Is null false
2. {!myVariable_old.Payment_Status__c} (false) Does not equal {!myVariable_current.Payment_Status__c} (true)
Logic: All conditions must be true (AND)

DECISION: myDecision
Executed this outcome: myRule_1
Outcome conditions: and
1. {!myVariable_current.FundRequests__c} (a057F000007KVvtQAG) Is null false
2. {!isChangedRule_2_myRule_1_Payment_Status_c} (true) Equals true
Logic: All conditions must be true (AND)

MDF_FLOW (FLOWS): myRule_1_A1
Inputs:
MDFRequestId = {!myVariable_current.FundRequests__c} (a057F000007KVvtQAG)