MCU error 5 (Loopback signal weak Please Help to me?

I am tryint to send any signal in gnu radio why I am taking this error ?
e[31;1m[FATAL] [UHDSoapyDevice] e[39;0mTx Calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)

I raised it, but nothing changed. What can I do about this error ?

I am trying to up gain with this code but it is giving to me error ?

root@kali:/usr/lib/uhd/examples# ./tx_samples_from_file --freq 915e6 --rate 5e6 --gain 70 usrp_samples.dat

Creating the usrp device with: …
[INFO] [UHD] linux; GNU C++ version 8.2.0; Boost_106700; UHD_3.13.1.0-3
[INFO] [UHDSoapyDevice] Make connection: ‘LimeSDR Mini [USB 2.0] 1D4C3893CE8AAC’
[INFO] [UHDSoapyDevice] Reference clock 40.00 MHz
[INFO] [UHDSoapyDevice] Device name: LimeSDR-Mini
[INFO] [UHDSoapyDevice] Reference: 40 MHz
[INFO] [UHDSoapyDevice] LMS7002M calibration values caching Disable
Using Device: Single USRP:
Device: FT601
Mboard 0: LimeSDR-Mini
RX Channel: 0
RX DSP: 0
RX Dboard: 0
RX Subdev: SoapyRF
TX Channel: 0
TX DSP: 0
TX Dboard: 0
TX Subdev: SoapyRF

Setting TX Rate: 5.000000 Msps…
Actual TX Rate: 5.000000 Msps…

Setting TX Freq: 915.000000 MHz…
Actual TX Freq: 915.000000 MHz…

Setting TX Gain: 70.000000 dB…
Actual TX Gain: 64.041200 dB…

Checking TX: LO Locked: …
[FATAL] [UHDSoapyDevice] Tx Calibration: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)
[WARNING] [UHDSoapyDevice] popping from TX, samples popped 0/1020