I don't understand 2 points

1 - I try to restart crunching with my little gpu (r7 260x), 'cause in the past
i crunched separation (modified_fit) with good results.
So, i create an app_info.xml file:

<app_info>
<app>
<name>milkyway</name>
</app>
<file_info>
<name>milkyway_1.36_windows_x86_64__opencl_ati_101.exe</name>
<executable />
</file_info>
<app_version>
<app_name>milkyway</app_name>
<version_num>136</version_num>
<avg_ncpus>1</avg_ncpus>
<max_ncpus>1</max_ncpus>
<plan_class>opencl_ati_101</plan_class>
<file_ref>
<file_name>milkyway_1.36_windows_x86_64__opencl_ati_101.exe</file_name>
<main_program/>
</file_ref>
</app_version>
<coproc>
<type>ATI</type>
<count>1.0000</count>
</coproc>
</app_info>

and copy "milkyway_1.36_windows_x86_64__opencl_ati_101.exe" in project's folder.
In my profile i select only "Use Ati Gpu" and only "Milkyway@Home" app, restart the boinc client and i have something like this: "You have selected not to receive work. Please change your preferences". So, i add "Use Cpu" to my profile and start to download wus.
In other gpu projects (seti, poem, einstein, etc) i see "Running (1 cpus+ 1 Ati gpu)", instead in MW i see "Local:open_cl" and i have to manualy free 1 cpu core to start the crunching. With gpu-z i see that gpu is at 100%, the wus finish after 57 seconds and in my profile i see "MilkyWay@Home Anonimous Platform (CPU)".
So, i'm crunching correctly with gpu?

2 - A some of this gpu(?) wus are "validation inconclusive"

Reading preferences ended prematurely
Guessing preferred OpenCL vendor 'Advanced Micro Devices, Inc.'
Error loading Lua script 'astronomy_parameters.txt': [string "number_parameters: 4..."]:1: '<name>' expected near '4'
Estimated AMD GPU GFLOP/s: 140 SP GFLOP/s, 28 DP FLOP/s
Warning: Bizarrely low flops (28). Defaulting to 100
Using a target frequency of 60.0
Using a block size of 3584 with 14 blocks/chunk
Using clWaitForEvents() for polling (mode -1)
Range: { nu_steps = 320, mu_steps = 800, r_steps = 700 }
Iteration area: 560000
Chunk estimate: 11
Num chunks: 12
Chunk size: 50176
Added area: 42112
Effective area: 602112
Initial wait: 13 ms
Integration time: 48.854621 s. Average time per iteration = 152.670689 ms
Integral 0 time = 49.085872 s
Running likelihood with 108460 stars
Likelihood time = 4.827398 s
<background_integral> 0.000243802200952 </background_integral>
<stream_integral> 69.274454862043314 278.012347645431870 58.133047973811458 </stream_integral>
<background_likelihood> -3.520008337647615 </background_likelihood>
<stream_only_likelihood> -5.953088899545048 -3.819500040662682 -3.709946426276413 </stream_only_likelihood>
<search_likelihood> -2.973975148077628 </search_likelihood>
22:47:29 (824): called boinc_finish

It's too little my gpu?