Are you using ProGuard's retrace.bat? It cannot deobfuscate stack traces that were obfuscated with DexGuard. Solution is to use DexGuard's retrace tool instead:
java -jar /var/DexGuard/lib/retrace.jar -verbose mapping.txt trace.txt
DexGuard's is backwards compatible, i.e., it can also retrace ProGuard obfuscated stack traces.