Getting type mismatch error

I am getting below error when adding multiple requests to exec, but when i add multiple methods to resource method i am not seeing any issue.

`

val searchCreatedCostCenter = exec(
CostCenterRequest.gridDataLoad("${NAME}"),
CostCenterRequest.simpleSave()
)

`

`

object CostCenterRequest{

def suggestGridDataLoad() : HttpRequestBuilder = {
Request.suggestGridDataLoad(“Cost Center Parent Suggest Grid”, Router.masterDataContext)

}

def simpleSave() : HttpRequestBuilder = {
Request.simpleSave(“Cost Center Simple Save”, Router.masterDataContext)
.formParamMap(session=>CostCenterFormParam.simpleSave(session))
.check(jsonPath("$.tbl0[0].costCenterRowId").find(0).saveAs(“COSTCENTER_ROWID”))
}

}

`