Technical Error when placing order

Hello.

I am getting an error when trying to place orders. This does not happen every time, and from the journal I can't see any pattern. Here is the journal log file:

21/04/2017 08:37:32.830 | cAlgo started
24/04/2017 08:56:56.331 | → Order OID20120993 is FILLED at 1.34462, position PID11331552 closed (24/04/2017 08:56:55.764 UTC+0)
24/04/2017 10:19:10.598 | Request to Buy £ 1k GBPUSD (Price: 1.28133, TP: 6, MR: 0) is sent to server
24/04/2017 10:19:11.848 | → Order OID20122860 is FILLED at 1.28124, position PID11332477 (24/04/2017 10:19:11.566 UTC+0)
24/04/2017 10:19:11.364 | → Request to Buy £ 1k GBPUSD (Price: 1.28133, TP: 6, MR: 0) is ACCEPTED, order OID20122860 created (24/04/2017 10:19:11.269 UTC+0)
24/04/2017 10:19:12.317 | → Stop order OID20122862 to Sell £ 2k GBPUSD (Price: 1.28074) is ACCEPTED (24/04/2017 10:19:12.075 UTC+0)
24/04/2017 10:19:12.082 | Stop order to Sell £ 2k GBPUSD (Price: 1.28074) is sent to server
24/04/2017 10:21:22.960 | Stop order to Buy £ 4k GBPUSD (Price: 1.28194) is sent to server
24/04/2017 10:21:22.804 | → Stop order to SELL £ 2k GBPUSD OID20122862 is FILLED at 1.28072, position PID11332478 (24/04/2017 10:21:22.474 UTC+0)
24/04/2017 10:21:23.397 | → Request to amend position PID11332477 (remove TP) is ACCEPTED
24/04/2017 10:21:23.225 | Request to amend position PID11332477 (remove TP) is sent to server
24/04/2017 10:21:23.022 | → Stop order OID20122874 to Buy £ 4k GBPUSD (Price: 1.28194) is ACCEPTED (24/04/2017 10:21:22.955 UTC+0)
24/04/2017 10:40:27.776 | Stop order to Sell £ 2k GBPUSD (Price: 1.28005) is sent to server
24/04/2017 10:40:27.870 | → Stop order OID20123001 to Sell £ 2k GBPUSD (Price: 1.28005) is ACCEPTED (24/04/2017 10:40:27.772 UTC+0)
24/04/2017 10:40:27.745 | → Order OID20122997 is FILLED at 1.28055, position PID11332535 (24/04/2017 10:40:27.663 UTC+0)
24/04/2017 10:40:27.401 | Request to Buy £ 1k GBPUSD (Price: 1.28055, TP: 6, MR: 0) is sent to server
24/04/2017 10:40:27.448 | → Request to Buy £ 1k GBPUSD (Price: 1.28055, TP: 6, MR: 0) is ACCEPTED, order OID20122997 created (24/04/2017 10:40:27.378 UTC+0)
24/04/2017 10:43:33.712 | → Stop order to SELL £ 2k GBPUSD OID20123001 is CANCELLED (24/04/2017 10:43:33.646 UTC+0)
24/04/2017 10:43:33.619 | Request to CANCEL order OID20123001 is sent to server
24/04/2017 10:43:33.400 | → Order OID20122999 is FILLED at 1.28121, position PID11332535 closed (24/04/2017 10:43:33.264 UTC+0)
24/04/2017 10:46:50.257 | → Stop order OID20123115 to Sell £ 8k GBPUSD (Price: 1.28004) is ACCEPTED (24/04/2017 10:46:50.198 UTC+0)
24/04/2017 10:46:50.194 | Stop order to Sell £ 8k GBPUSD (Price: 1.28004) is sent to server
24/04/2017 10:46:50.116 | → Stop order to BUY £ 4k GBPUSD OID20122874 is FILLED at 1.28194, position PID11332483 (24/04/2017 10:46:50.068 UTC+0)
24/04/2017 10:51:20.836 | Request to close position PID11332478 is sent to server
24/04/2017 10:51:20.961 | → Request to close position PID11332478 is ACCEPTED, order OID20123171 created (24/04/2017 10:51:20.848 UTC+0)
24/04/2017 10:51:20.820 | → Order OID20123170 is FILLED at 1.28254, position PID11332477 closed (24/04/2017 10:51:20.720 UTC+0)
24/04/2017 10:51:20.429 | Request to close position PID11332477 is sent to server
24/04/2017 10:51:20.539 | → Request to close position PID11332477 is ACCEPTED, order OID20123170 created (24/04/2017 10:51:20.450 UTC+0)
24/04/2017 10:51:21.617 | → Order OID20123172 is FILLED at 1.28254, position PID11332483 closed (24/04/2017 10:51:21.460 UTC+0)
24/04/2017 10:51:21.664 | Request to CANCEL order OID20123115 is sent to server
24/04/2017 10:51:21.726 | → Stop order to SELL £ 8k GBPUSD OID20123115 is CANCELLED (24/04/2017 10:51:21.646 UTC+0)
24/04/2017 10:51:21.226 | → Order OID20123171 is FILLED at 1.28258, position PID11332478 closed (24/04/2017 10:51:21.112 UTC+0)
24/04/2017 10:51:21.226 | Request to close position PID11332483 is sent to server
24/04/2017 10:51:21.336 | → Request to close position PID11332483 is ACCEPTED, order OID20123172 created (24/04/2017 10:51:21.246 UTC+0)
24/04/2017 11:46:24.691 | → Request to Buy £ 1k GBPUSD (Price: 1.28088, TP: 6, MR: 0) is ACCEPTED, order OID20127658 created (24/04/2017 11:46:24.653 UTC+0)
24/04/2017 11:46:24.613 | Request to Buy £ 1k GBPUSD (Price: 1.28088, TP: 6, MR: 0) is sent to server
24/04/2017 11:46:25.269 | → Order OID20127658 is REJECTED with error ""

You can see there is a request to buy right at the end that fails. I had no other robots running so I don't think this is margin related, and not quantity related and there are other orders filled of the same value.

Why is this happening?

Thank you.