Unable to process application "Gamma-ray pulsar search #3 v1.11 (FGRPopencl-ati)".

Application starts OK then, about 10-20 seconds later, always ends with "Error while computing".

Please note that "Gamma-ray pulsar search #3 v1.11 (FGRPSSE) run OK" and "Binary Radio
Pulsar Search (Perseus Arm Survey) v1.39 (BRP5-opencl-ati)" also run OK.

Computer info:
GenuineIntel Pentium(R) Dual-Core CPU E6500 @ 2.93GHz [Family 6 Model 23 Stepping 10]
Number of processors 2
Coprocessors CAL AMD Radeon HD 6350/6450/7450/7470 series (Caicos) (1024MB) driver: 1.4.1741
Note: my GPU card is HD6450 (single precision FP)

Operating System Linux Mint 16 (Petra) 64-bit
3.2.0-61-generic
BOINC client version 7.2.42
Memory 3954.38 MB

Stderr output (from Einstein@Home task)

Using OpenCL platform provided by: Advanced Micro Devices, Inc.
Using OpenCL device "Caicos" by: Advanced Micro Devices, Inc.
Max allocation limit: 134217728
% Opening inputfile: ../../projects/einstein.phys.uwm.edu/LATeah0092C.dat
% Total amount of photon times: 10000
% Preparing toplist of length: 5
read_checkpoint(): Couldn't open file 'results.cand.out.cpt': No such file or directory (2)
% fft_size: 33554432 (0x2000000)
% Sky point 1/99
% Creating FFT plan.
Error allocating device memory: 268435456 bytes (error: -61)
21:32:59 (2510): [CRITICAL]: ERROR: MAIN() returned with error '1'

As you can see application tries to allocate 268435456 bytes but driver (?) limits the Max allocation to 134217728 bytes
hence the error "Error allocating device memory: 268435456 bytes (error: -61)"

Actions:
I tried several driver versions, besides the Ubuntu (Mint uses the same driver) driver available in the repository (fglrx-updates version 2:13.101-0ubuntu3),
including the 14.x drivers available at AMD site but none solved the memory allocation limitation.
I have opened a thread at Einstein@Home forum but the analysis has come to a halt due to lack of knowledge regarding the inner workings of a driver.

Additional info:
Dom 25 Mai 2014 15:08:22 BRT | | CAL: ATI GPU 0: AMD Radeon HD 6350/6450/7450/7470 series (Caicos) (CAL version 1.4.1741, 1024MB, 933MB available, 400 GFLOPS peak)
Dom 25 Mai 2014 15:08:22 BRT | | OpenCL: AMD/ATI GPU 0: AMD Radeon HD 6350/6450/7450/7470 series (Caicos) (driver version 1214.3, device version OpenCL 1.2 AMD-APP (1214.3), 1024MB, 933MB available, 400 GFLOPS peak)

>clinfo (truncated)
Number of platforms: 1
Platform Profile: FULL_PROFILE
Platform Version: OpenCL 1.2 AMD-APP (1214.3)
Platform Name: AMD Accelerated Parallel Processing
Platform Vendor: Advanced Micro Devices, Inc.
Platform Extensions: cl_khr_icd cl_amd_event_callback cl_amd_offline_devices
.
.
Platform Name: AMD Accelerated Parallel Processing
Number of devices: 2
Device Type: CL_DEVICE_TYPE_GPU
Device ID: 4098
Board name: AMD Radeon HD 6450
Device Topology: PCI[ B#1, D#0, F#0 ]

Max clock frequency: 625Mhz
Address bits: 32
Max memory allocation: 134217728
.
.
Global memory size: 536870912

From my point of view Global memory size: 536870912 which is 50% of total memory (1024 MB)
but Max memory allocation: 134217728 which is about 13% of total memory.

Question: why 'Global memory size' of 536870912 bytes? The GPU card is supposed to have 1024 MB.

Any suggestions will be greatly appreciated.
Thanks in advance.
Sergio.