Jquery 获取datatables中选定行中第一列的值

我试图使用DataTables获取select行的第一列的值。我读过很多关于这个的帖子和解决方案。它应该很简单，但是每当我使用“…data（）”方法时，我都会得到一个“。。。。是“未定义”错误

第一列包含键，我将使用它获取详细记录并显示在相邻的选项卡中。然而，我已经尝试了很多东西，但似乎无法获得价值

该表由API调用返回的数据填充，工作正常。HTML中的结构如下所示：

<table id="Proposal-table" class="table table-hover non-hover"
       data-toggle="Proposal-table" style="width:100%">
       <thead>
          <tr>
             <th data-field="ID_PROPOSAL" id="ID">ID</th>
             <th data-field="STR_INST_REF">Institution</th>
             <th data-field="NME_PROPOSAL">Name</th>
             <th data-field="STR_DESC" data-width="900" data-widthunit="px">Description</th>
             <th data-field="CNT_TERM">Term</th>
             <th data-field="AMT_TOTAL_VALUE">Value</th>
             <th data-field="AMT_TOTAL_COST">Cost</th>
             <th data-field="CCY_PROPOSAL">CCY.</th>
             <th data-field="PCT_INT_RATE_LOW">Rate Low</th>
             <th data-field="PCT_INT_RATE_HIGH">Rate High</th>
             <th data-field="IND_PROD_TYPE">Type</th>
             <th data-field="IND_STATUS">Status</th>
             <th data-field="DTE_CREATED">Created</th>
             <th data-field="DTM_MAINT">Maint</th>
             <!--    <th>Action TBC</th> -->
         </tr>
    </thead>
 </table>

然后，我能够使用以下方法成功访问row（）.data（）方法：

      //Make table Clickable and process click...
      $('#Proposal-table tbody').on('click', 'tr', function() {
          var dta = propTable.row( this ).data();
          var id = dta["ID_PROPOSAL"];

          "ajax": {
              "url":"http://path to data/proposal/list/",
              "type":"GET",
              "dataSrc": "output"
          },
          columns:[
              { data: "ID_PROPOSAL"},
              { data: "STR_INST_REF"},
              { data: "NME_PROPOSAL"},
              { data: "STR_DESC"},
              { data: "CNT_TERM"},
              { data: "AMT_TOTAL_VALUE"},
              { data: "AMT_TOTAL_COST"},
              { data: "CCY_PROPOSAL"},
              { data: "CNT_USER_ID"},
              { data: "PCT_INT_RATE_LOW"},
              { data: "PCT_INT_RATE_HIGH"},
              { data: "IND_PROD_TYPE"},
              { data: "IND_STATUS"},
              { data: "DTE_CREATED"},
              { data: "DTM_MAINT"},
          ],
          select: true,

      //Make table Clickable and process click...
      $('#Proposal-table tbody').on('click', 'tr', function() {
          var dta = propTable.row( this ).data();
          var id = dta["ID_PROPOSAL"];