Error showing when search a save search with filter

Hello,

I do have a save search to search a custom record in account. There are certain fields in that custom record. When trying to search that save search applying filters to any field, it shows me error as

Code: SSS_INVALID_SRCH_FILTER Details: An nlobjSearchFilter contains invalid search criteria: custrecord_header_customer_id

where "custrecord_header_customer_id" is the field sourced the customers.

I have a feeling that it accepts the numbers/internal ids as this field is a list/record type. I am not sure about that error.

Code for filter :

var filters = new Array();
filters[0] = new nlobjSearchFilter('custrecord_header_customer_id ', null, 'is', endCustomer);  // endCustomer is a number here.