Invalid Parameter Value ro

Invalid Parameter Value ro

I am trying to rollup the $ of several items from a Custom Module to the Potentials Module. Here is my script (very similar to your Potentials rollup to Account example:

My only Custom Module is "ProductLineItem" with 

Here are my arguments:
Sumup field is LineItemTotals
potentialid is Potential ID

Here is my script:
potentialid1=input.potentialid.toString();
resp = zoho.crm.searchrecordsbypdc("custommodule1","Opportunity",potentialid1);
info resp;
total=0.0;
for each rec in resp
{
total=(total  +  (rec.get("Amount")).toDecimal());
}
updateResp = zoho.crm.updateRecord("Potentials",potentialid1,{ input.sumupfield : total });

Here is what I get:
Execution Failed
Error occured please contact application owner.
Log messages:
{"4832":"Invalid parameter value"}