DataTable query not working

I keep getting a type error when trying to query a DataTable.

Please see my code below:

******************************************************

var params = {
NameOfOrgUnit: UserSelectedOrgUnit /* STRING */
};

//base type of nameOfDataTable is THINGNAME
var nameOfDataTable = me.getDataTableNameBasedOnOrgUnit(params);

var query = {
"filters": {
"fieldName": "customerName",
"type": "EQ",
"value": UserInputCustomerName //STRING
}
};

var params = {
maxItems: undefined /* NUMBER */,
values: undefined /* INFOTABLE*/,
query: query /* QUERY */,
source: undefined /* STRING */,
tags: undefined /* TAGS */
};

// result: INFOTABLE dataShape: "undefined"
var result = nameOfDataTable.QueryDataTableEntries(params);

**********************************************************

I've tried setting the output of the service DataTableNameBasedOnOrgUnit to STRING and THINGNAME; however, I keep getting a script error that says the following:

if output is STRING: "[message: Execution error in service script [checkIfCustomerNameExists] :: TypeError: Cannot find function QueryDataTableEntries in object SFG.Customer.Norway.DT. (checkIfCustomerNameExists#25)]"

if output is THINGNAME: "[message: Execution error in service script [checkIfCustomerNameExists] :: TypeError: Cannot call method "QueryDataTableEntries" of null (checkIfCustomerNameExists#25)]"