FIX: valgrind reported this one:

FIX: valgrind reported this one:
UMR ==23598== Use of uninitialised value of size 4
==23598==    at 0x77C5B7: isalpha (in /lib/tls/libc-2.3.2.so)
==23598==    by 0x3C2CAB2E: gdcmDocument::FindDocEntryVR(gdcmDocEntry*) (gdcmDocument.cxx:1783)
==23598==    by 0x3C2CCE83: gdcmDocument::ReadNextDocEntry() (gdcmDocument.cxx:2556)
==23598==    by 0x3C2C985C: gdcmDocument::ParseSQ(gdcmSeqEntry*, long, long, bool) (gdcmDocument.cxx:1422)
==23598==    by 0x3C2C9792: gdcmDocument::ParseDES(gdcmDocEntrySet*, long, long, bool) (gdcmDocument.cxx:1391)
==23598==    by 0x3C2C5858: gdcmDocument::gdcmDocument(std::string const&, bool, bool, bool) (gdcmDocument.cxx:130)
==23598==    by 0x3C2B19FA: gdcmHeader::gdcmHeader(std::string const&, bool, bool, bool) (gdcmHeader.cxx:47)
==23598==    by 0x8053824: PrintAllDocument(int, char**) (PrintAllDocument.cxx:34)
==23598==    by 0x8050D3E: main (gdcmTests.cxx:173)
==23598==