Cannot Set Tx Mode in LoRa mode

Hi, i was making a porting of the Arduino library for the LoRa module (using SX1276) to run it in the TSM320F28379D board of Texas Instruments. I copy-pasted the Arduino library functions, changing just the SPI function to adapt to the board. Everything seemed fine, i could both read and write the registers, change between SLEEP and STANDBY mode, but when i tried to send datas, i couldn’t change in TX mode, and the module manteined the Standby status. Is there a reason for this behaviour?