How to find a variable just after a marker?

Dear experts,

My project steps further - but as soon as I have to deal with FM-objects I still struggle. The script should do this:

• In the document (http://www.daube.ch/zz_tests/Markers-and-variables.fm) there are markers of type #calc (which are all found and stored into an array.
• Some of them are immediately followed by a variable (called temporary variable, because the names are built by date/time).
• Before I insert the new variable, the old one should be found and removed.
• The problem is that I do not find the old variable and hence can not remove it, before the new one is inserted. The inserting is OK, but it occurs independently of existing variables.
• Line 49 always evaluates to false, even if there is a variable present.

How can I find (at first hand) any variable (Later I will need to check whether it is really a temprary variable) ?

#target framemaker
// Required doc: Markers-and-variables.fm:
  aVariables = ["#DOCname", "#TEST", "2016-09-27T10:28:46.060Z"];
  goCurrentDoc =  app.ActiveDoc;
  giNCalcMarkers = CollectMarkers  (gaoCalcMarkers, "#calc");

for (j = 0; j < giNCalcMarkers; j++) {
  goCurrentMarker = gaoCalcMarkers;            // find a marker
  oFound = FindVariable (goCurrentDoc, goCurrentMarker);
  if (oFound[0]) {                                // true, variable found
    oFound[1].Delete();                           // remove temp. variable from document
  }
  oTextLoc = goCurrentMarker.TextLoc;
  oTextLoc.offset = oTextLoc.offset + 1;          // insert temp variable behind marker
  InsertVariable (goCurrentDoc, oTextLoc, "#TEST", "\+1.275×10<super>\+9" );
}
// ================= Routines to be tested ========================================================
function CollectMarkers (aMarkers, sMarkerName) { //=== Collect marker-objects, store in array ====
// In        aMarkers:    global array of markers to be filled
//           sMarkerName: type of marker to be collected
// Out       Return number of markers collected
var  oMarker, MarkerTI, nMarkers;
  tsSave = goCurrentDoc.TextSelection;            // save current cursor location
  oMarker = goCurrentDoc.FirstMarkerInDoc;
  while (oMarker.ObjectValid()) {
    MarkerTI = oMarker.MarkerTypeId;
    if (MarkerTI.Name == sMarkerName) {
      aMarkers.push(oMarker);                     // store the marker objects 
    }
    oMarker = oMarker.NextMarkerInDoc;
  }
  goCurrentDoc.TextSelection = tsSave;            // Restore cursor location 
  nMarkers = aMarkers.length;
  return nMarkers;                                // number of markers in array
} //--- end CollectMarkers  

function FindVariable (oDoc, oMarker) { //=== Find variable behind marker ========================
// In        oMarker: current marker
// Out       Function returns [true, found variable] or [false, loc behind the marker]
var tLoc1 = oMarker.TextLoc,
    tLoc2 = oMarker.TextLoc,                      // should be just behind the marker
    j, myTextRange, findParams, fRange, oTextItem, aVarsRange, nVars, thisVar;  
  tLoc1.offset = tLoc1.offset + 1;
  tLoc2.offset = tLoc2.offset + 2;
  myTextRange  = new TextRange(tLoc1,tLoc2);
  oDoc.TextSelection = myTextRange;               // Does this hold a variable ?
  findParams= GetFindParamsVariable ("");         // search for any variable
  fRange = goCurrentDoc.Find  (tLoc1, findParams);// is a textrange
  if (fRange.beg.obj.ObjectValid()) {
    aVarsRange = goCurrentDoc.GetTextForRange (fRange, Constants.FTI_VarBegin);
    nVars = aVarsRange.length;
    for (j = 0; j < nVars; j++) {                   // loop should not be necessary
      oTextItem = aVarsRange;                    // superfluous ?
      thisVar = oTextItem.obj;                      // should contain only one variable
      return [true, thisVar];
    }
  } else {
    return [false, tLoc1];
  }
} //--- end FindVariable  

function GetFindParamsVariable (sVarName) { //=== Set up parameters to Find variable ==============
// In        sVarName: variable type to be found
// Out       Returns parameters for the find function: no wrapping around ?
var findParams;
  findParams = AllocatePropVals (2);  
  findParams[0].propIdent.num = Constants.FS_FindWrap ;  
  findParams[0].propVal.valType = Constants.FT_Integer;  
  findParams[0].propVal.ival = 0 ; // don't start at the beginning => seems to be 'nowrap'
  findParams[1].propIdent.num = Constants.FS_FindNamedVariable;  
  findParams[1].propVal.valType = Constants.FT_String;  
  findParams[1].propVal.sval = sVarName;  
  return findParams;  
} //--- end GetFindParams

function InsertVariable (oDoc, oTextLoc, sVarName, sContent) { //=== Insert variable at location =====
// In        oTextLoc: where to insert the variable 
//           sVarName: name of the variable
//           sContent: content of the variable
var oVar;  
  oVar = oDoc.NewAnchoredFormattedVar (sVarName, oTextLoc);  
  oVar.Fmt = sContent; 
}