# Error running loopback **URL:** \ **Category:** GNU Radio\ **Created:** [April 29, 2014, 10:12pm UTC](https://www.ruby-forum.com/t/error-running-loopback/240767 "2014-04-29T22:12:09Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [April 29, 2014, 10:12pm UTC](https://www.ruby-forum.com/t/error-running-loopback/240767/1 "2014-04-29T22:12:09Z")
per my last: Tried running the loopback example, get comparable error message: linux; GNU C++ version 4.6.3; Boost\_104800; UHD\_003.007.000-133-g6bd9fed2 Using Volk machine: avx\_64\_mmx\_orc – Opening a USRP1 device… – Using FPGA clock rate of 64.000000MHz… thread[thread-per-block[4]: \]: LookupError: KeyError: Cannot find an item size: thread[thread-per-block[5]: \]: LookupError: KeyError: Cannot find an item size: – “The power of accurate observation is commonly called cynicism by those who have not got it.” -George Bernard Shaw Dr. Don L. AJ7LL Six Mile Systems LLC 17850 Six Mile Road Huson, MT, 59846 mail: POBox 404 Frenchtown MT 59834-0404 VOX 406-626-4304 Skype: buffler2 [www.lightningforensics.com](http://www.lightningforensics.com) [www.sixmilesystems.com](http://www.sixmilesystems.com) ---
**Author:** ![Don\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@Don\_L](https://www.ruby-forum.com/u/Don_L)\ **Post date:** [April 30, 2014, 12:10am UTC](https://www.ruby-forum.com/t/error-running-loopback/240767/2 "2014-04-30T00:10:23Z")
On Tue, Apr 29, 2014 at 3:10 PM, Don L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > 17850 Six Mile Road > Huson, MT, 59846 > mail: POBox 404 > Frenchtown MT 59834-0404 > VOX 406-626-4304 > Skype: buffler2 > [www.lightningforensics.com](http://www.lightningforensics.com) > [www.sixmilesystems.com](http://www.sixmilesystems.com) This is a bug and has since been fixed. See the other post about 2 hours ago with the same error: > **[Re: \[Discuss-gnuradio\] using uhd\_fft with USRP1](https://lists.gnu.org/archive/html/discuss-gnuradio/2014-04/msg00492.html)** This seems like a popular topic! Nathan