“当调用 .to_ex 时，“未处理异常：至少一个工作表必须可见。”

Question

我正试图在同一个excel文件中写入多个工作表。我正在使用ExcelWriter，当我调用.to\u excel时，我收到以下错误：“至少有一个工作表必须可见。”。下面是我要运行的代码：

 pathresults = "C:/Users/SVR/SVRresults/"
 filesufix = str(_kernel)
    filenameTRpred='predicted_train_'+ filesufix + '.xlsx'
    filenameTEpred='PredictedNewData_'+ filesufix +'.xlsx'
    with pd.ExcelWriter(filenameTRpred) as TR_writer:
        with pd.ExcelWriter(filenameTEpred) as TE_writer:

# unrelated code...

sheetName = "no-degree_" + str(_C) + "_" + str(_epsilon) 
# _C and _epsilon are float values
export_excel_TR = delta.to_excel (TR_writer, pathresults+filenameTRpred, index = None, header=True, sheet_name = sheetName) # this line triggers the error