Segmentation Fault for function resolved by QLibrary?

[CAD_coding]

I am loading OpenCL.dll at run time using QLibrary.

@QLibrary *MyOpenCL::openCLLibrary = NULL;

bool MyOpenCL::loadOpenCL()
{
if(openCLLibrary)
return true;

QLibrary *lib = new QLibrary("OpenCL");
if(!lib->load())
    return false;

bool result = false;
typedef cl_int (*MyPlatorms)(cl_uint, cl_platform_id *, cl_uint *);
MyPlatorms pobj = (MyPlatorms) lib->resolve("clGetPlatformIDs");
if(pobj)
{
    cl_uint nplatforms = 0;
    cl_uint myerr = pobj(INT_MAX, NULL, &nplatforms);
    if((myerr == CL_SUCCESS) && (nplatforms > 0))
    {
        cl_platform_id *mplatforms = new cl_platform_id[nplatforms];
        {
            const cl_uint csize = nplatforms;
            myerr = pobj(csize, mplatforms, &nplatforms);
        }

        typedef cl_int (*MyPlatformInfo)(cl_platform_id, cl_platform_info, size_t, void *, size_t *);
        MyPlatformInfo pinfoobj = (MyPlatformInfo) lib->resolve("clGetPlatformInfo");
        if(pinfoobj)
        {
            size_t size;
            for(unsigned int i = 0; i < nplatforms; i++)
            {
                size = 0;
                myerr = pinfoobj(mplatforms[i], CL_PLATFORM_VERSION, 0, NULL, &size);//line A
                if(size < 1)
                    continue;

                char *ver = new char[size];
                {
                    const size_t csize = size;
                    myerr = pinfoobj(mplatforms[i], CL_PLATFORM_VERSION, csize, ver, &size);//line B
                }

...
}@

When I am debugging at line B it jumps to line A and shows the Segmentation Fault error.
I have spent 8 hours figuring this one out and so far I have had no luck.
I am running Windows7 with MinGW compiler and my ATI 7670m has OpenCL 1.1 drivers.
Please suggest me how to solve my problem?