diff --git a/src/classes/PFitter.cpp b/src/classes/PFitter.cpp
index 44eb3d0d..3ce534ab 100644
--- a/src/classes/PFitter.cpp
+++ b/src/classes/PFitter.cpp
@@ -280,19 +280,19 @@ bool PFitter::SetParameters()
     } else { // add free parameter
       // check if boundaries are given
       if (fParams[i].fNoOfParams > 5) { // boundaries given
-cout << endl << ">> name=" << fParams[i].fName.Data() << ", lower=" << fParams[i].fLowerBoundaryPresent << ", upper=" << fParams[i].fUpperBoundaryPresent;
+//cout << endl << ">> name=" << fParams[i].fName.Data() << ", lower=" << fParams[i].fLowerBoundaryPresent << ", upper=" << fParams[i].fUpperBoundaryPresent;
         if (fParams[i].fLowerBoundaryPresent && 
             fParams[i].fUpperBoundaryPresent) { // upper and lower boundaries given
-cout << endl << ">> lower and upper";
+//cout << endl << ">> lower and upper";
           fMnUserParams.Add(fParams[i].fName.Data(), fParams[i].fValue, fParams[i].fStep,
                             fParams[i].fLowerBoundary, fParams[i].fUpperBoundary);
         } else if (fParams[i].fLowerBoundaryPresent && 
                    !fParams[i].fUpperBoundaryPresent) { // lower boundary limited
-cout << endl << ">> lower only";
+//cout << endl << ">> lower only";
           fMnUserParams.Add(fParams[i].fName.Data(), fParams[i].fValue, fParams[i].fStep);
           fMnUserParams.SetLowerLimit(fParams[i].fName.Data(), fParams[i].fLowerBoundary);
         } else { // upper boundary limited
-cout << endl << ">> upper only";
+//cout << endl << ">> upper only";
           fMnUserParams.Add(fParams[i].fName.Data(), fParams[i].fValue, fParams[i].fStep);
           fMnUserParams.SetUpperLimit(fParams[i].fName.Data(), fParams[i].fUpperBoundary);
         }
@@ -301,7 +301,7 @@ cout << endl << ">> upper only";
       }
     }
   }
-cout << endl;
+//cout << endl;
 
   // check if there is an unused parameter, if so, fix it
   for (unsigned int i=0; i<fParams.size(); i++) {
diff --git a/src/classes/PTheory.cpp b/src/classes/PTheory.cpp
index 7c1298b2..653ddac3 100644
--- a/src/classes/PTheory.cpp
+++ b/src/classes/PTheory.cpp
@@ -684,6 +684,7 @@ void PTheory::MakeCleanAndTidyTheoryBlock(PMsrLines *fullTheoryBlock)
     line = &(*fullTheoryBlock)[i];
     // copy line content to str in order to remove comments
     str = line->fLine.Copy();
+cout << endl << ">> str = " << str.Data();
     // remove theory line comment if present, i.e. something starting with '('
     int index = str.Index("(");
     if (index > 0) // theory line comment present
@@ -696,16 +697,16 @@ void PTheory::MakeCleanAndTidyTheoryBlock(PMsrLines *fullTheoryBlock)
     str = ostr->GetString();
     // check if the line is just a '+' if so nothing to be done
     if (str.Contains("+"))
-      return;
+      continue;
     // check if the function is a polynom
     if (!str.CompareTo("p") || str.Contains("polynom")) {
       MakeCleanAndTidyPolynom(i, fullTheoryBlock);
-      return;
+      continue;
     }
     // check if the function is a userFcn
     if (!str.CompareTo("u") || str.Contains("userFcn")) {
       MakeCleanAndTidyUserFcn(i, fullTheoryBlock);
-      return;
+      continue;
     }
     // search the theory function
     for (unsigned int j=0; j<THEORY_MAX; j++) {
@@ -1324,11 +1325,11 @@ double PTheory::Bessel(register double t, const PDoubleVector& paramValues, cons
  */
 double PTheory::InternalBessel(register double t, const PDoubleVector& paramValues, const PDoubleVector& funcValues) const
 {
-  // expected parameters: phase frequency rateT rateL [tshift]
+  // expected parameters: fraction phase frequency rateT rateL [tshift]
 
-  double val[5];
+  double val[6];
 
-  assert(fParamNo.size() <= 5);
+  assert(fParamNo.size() <= 6);
 
   // check if FUNCTIONS are used
   for (unsigned int i=0; i<fParamNo.size(); i++) {
@@ -1340,15 +1341,14 @@ double PTheory::InternalBessel(register double t, const PDoubleVector& paramValu
   }
 
   double tt;
-  if (fParamNo.size() == 4) // no tshift
+  if (fParamNo.size() == 5) // no tshift
     tt = t;
   else // tshift present
-    tt = t-val[4];
+    tt = t-val[5];
 
-  return 0.666666666666667*
-                 TMath::BesselJ0(DEG_TO_RAD*val[0]+TWO_PI*val[1]*tt)*
-                 TMath::Exp(-val[2]*tt) +
-         0.333333333333333*TMath::Exp(-val[3]*tt);
+  return val[0]* TMath::BesselJ0(DEG_TO_RAD*val[1]+TWO_PI*val[2]*tt)*
+                 TMath::Exp(-val[3]*tt) +
+         (1.0-val[0])*TMath::Exp(-val[4]*tt);
 }
 
 //--------------------------------------------------------------------------
diff --git a/src/include/PTheory.h b/src/include/PTheory.h
index 83265305..090cecae 100644
--- a/src/include/PTheory.h
+++ b/src/include/PTheory.h
@@ -87,7 +87,7 @@
 #define THEORY_PARAM_INTERNAL_FIELD               4 // phase, frequency, TF damping, damping (tshift)
 #define THEORY_PARAM_TF_COS                       2 // phase, frequency (tshift)
 #define THEORY_PARAM_BESSEL                       2 // phase, frequency (tshift)
-#define THEORY_PARAM_INTERNAL_BESSEL              5 // fraction, phase, frequency, TF damping, damping (tshift)
+#define THEORY_PARAM_INTERNAL_BESSEL              5 // fraction, phase, frequency, TF damping, LF damping (tshift)
 #define THEORY_PARAM_SKEWED_GAUSS                 4 // phase, frequency, rate minus, rate plus (tshift)
 
 // number of available user functions
@@ -163,7 +163,7 @@ static PTheoDataBase fgTheoDataBase[THEORY_MAX] = {
          "bessel", "b", "(phase frequency)", "(phase frequency tshift)"},
 
         {THEORY_INTERNAL_BESSEL, THEORY_PARAM_INTERNAL_BESSEL, false,
-         "internBsl", "ib", "(phase frequency Trate Lrate)", "(phase frequency Trate Lrate tshift)"},
+         "internBsl", "ib", "(fraction phase frequency Trate Lrate)", "(fraction phase frequency Trate Lrate tshift)"},
 
         {THEORY_SKEWED_GAUSS, THEORY_PARAM_SKEWED_GAUSS, false,
          "skewedGss", "skg", "(phase frequency rate_m rate_p)", "(phase frequency rate_m rate_p tshift)"},