QSqlDatabase::drivers() do not output same in debug and release

[isml]

Qt Version : 5.1.1 VS 2010, downloaded from qt-project
I compiled the oci driver by myself. After that, I check the sqldrivers dir:
2013/08/26 02:58 620,032 qsqlite.dll
2013/08/26 02:58 880,640 qsqlited.dll
2013/08/26 02:58 2,305,024 qsqlited.pdb
2013/11/12 12:50 47,104 qsqlmysql.dll
2013/11/12 12:50 2,024 qsqlmysql.lib
2013/11/12 13:10 1,227 qsqlmysql.prl
2013/11/12 12:50 112,128 qsqlmysqld.dll
2013/11/12 12:50 2,040 qsqlmysqld.lib
2013/11/12 12:50 1,166,336 qsqlmysqld.pdb
2013/11/12 13:10 1,200 qsqlmysqld.prl
2013/11/12 12:50 76,800 qsqloci.dll
2013/11/12 11:26 311,532 qsqloci.lib
2013/11/12 11:26 1,130 qsqloci.prl
2013/11/12 12:50 151,552 qsqlocid.dll
2013/11/12 11:26 602,318 qsqlocid.lib
2013/11/12 12:50 1,141,760 qsqlocid.pdb
2013/11/12 11:26 1,103 qsqlocid.prl
2013/08/26 02:58 66,048 qsqlodbc.dll
2013/08/26 02:58 138,240 qsqlodbcd.dll
2013/08/26 02:58 1,149,952 qsqlodbcd.pdb
2013/08/26 02:58 53,248 qsqlpsql.dll
2013/08/26 02:58 104,448 qsqlpsqld.dll
2013/08/26 02:58 1,035,264 qsqlpsqld.pdb

and I write a sample app:
QStringList ar = QSqlDatabase::drivers();
for(int i = 0, nCount = ar.size(); i < nCount; ++ i)
{
qDebug() << ar.at(i);
}

in debug:

"QSQLITE"
"QMYSQL"
"QMYSQL3"
"QODBC"
"QODBC3"
"QPSQL"
"QPSQL7"

in release:
"QSQLITE"
"QMYSQL"
"QMYSQL3"
"QOCI"
"QOCI8"
"QODBC"
"QODBC3"
"QPSQL"
"QPSQL7"

The problem is that QOCI is not found in debug version. Why?
Thanks in advance.