title: Python RRDTool update error Function update_pdp_prep, case DST_GAUGE - Cannot convert '' to float
body: <pre><code>def updateRRD(self,fname,value):
          PATH_TO_RRD_FILES = "/home/nms/SNMP-DATA/RRD-DB/" 
          rrdtool.update(str(PATH_TO_RRD_FILES)+str(fname)+".rrd","N:"+str(value))
  </code></pre>
  
  <p>Above is my rrdtool update function that takes value returned by snmp commands(value) and the filename in the db.</p>
  
  <p>At first it was running but now it always shows this error and as i m new to this tool aI cant figure it out.</p>
  
  <p>Any suggestions?</p>