Hi vladan23,
What error message are you receiving when you try to download your VI to the 8186? Have you updated all the drivers on the 8186? The easiest way to check this is in MAX, just compare the software versions under My System>>Software, to Remote Systems>>(name of your PXI-8186 system)>>Software. If your 8186 is missing software, simply right-click on the Remote Systems>>(name of your PXI-8186 system)>>Software folder and select "Add Software", and then select the necessary software to download from the host system to the 8186. I imagine that the drivers are not updated on the target, which is why the host PC runs the application fine, but the target does not. Please refer to the drivers page for LabVIEW RT, to make sure you have all the up-to date drivers:
LabVIEW Real-Time (RT) Driver Support
http://www.ni.com/support/labview/real-time/drivers.htm
You could also try to download a very simple LabVIEW RT program to your 8186 that doesn't use any hardware, just to see if it's the IMAQ specific functions that are causing the problem (due to the driver not being installed). But in general, your process of downloading the application appears to be correct.
Best Regards,
Jeff M.
Applications Engineering
National Instruments