Crash calling glGetTexImage (at glgVectorCopy ?)

I'm trying to use GetTexImage together with a PBO: without success.

I am not able to out what I am doing wrong.

Whenever I bind the buffer and then call GetTexImage my app crashes with EXC_BAD_ACCESS on glgVectorCopy.

Calling GetTexImage without a bound PBO works fine, but slow.

I've tried this on 3 different Intel macs - all fail.

The code:

#define BUFFER_OFFSET(i) ((char *)NULL + (i))

...

GLuint _Tex;

GLuint _downloadPBO;

glGenTextures(1, & _Tex);

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _Tex);

glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

glTexParameteri(GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA8, _width, _height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, NULL);

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);

glGenBuffers(1 , & _downloadPBO);

glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, _downloadPBO);

glBufferData(GL_PIXEL_PACK_BUFFER_ARB, _width * _height * 4, NULL, GL_STREAM_READ);

glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);

...

I upload the texture data using another PBO => this is working fine!.

...

glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, _downloadPBO);

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, _Tex);

glGetTexImage(GL_TEXTURE_RECTANGLE_ARB, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, BUFFER_OFFSET(0)); <= this crashes!

glBindTexture(GL_TEXTURE_RECTANGLE_ARB, 0);

glBindBuffer(GL_PIXEL_PACK_BUFFER_ARB, 0);

Any help is welcome :) Mark