Index: /trunk/FACT++/src/biasctrl.cc
===================================================================
--- /trunk/FACT++/src/biasctrl.cc	(revision 11972)
+++ /trunk/FACT++/src/biasctrl.cc	(revision 11973)
@@ -806,5 +806,7 @@
             if (fVoltRef[ch]+dac[ch]>kMaxDac)
             {
-                Error("AddDac - New voltage reference out of range.");
+                ostringstream msg;
+                msg << "AddDac - New voltage reference of " << fVoltRef[ch]*90./4096 << "V + " << dac[ch]*90./4096. << "V for channel " << ch << " out of range.";
+                Error(msg);
                 return false;
             }
@@ -914,5 +916,7 @@
             if (fVoltGapd[ch]+dac>kMaxDac)
             {
-                Error("SetGapdVoltage - New voltage reference out of range.");
+                ostringstream msg;
+                msg << "SetGapdVoltage - New voltage reference of " << fVoltGapd[ch] << "V + " << dac << "V for channel " << ch << " out of range.";
+                Error(msg);
                 return false;
             }