STM32 F103xx HAL UART echo

I am trying to implement a simple echo program using the HAL drivers. Here is my code

#include 'stm32f1xx.h'
#include 'stm32f1xx_hal.h'
#include 'stm32f1xx_hal_conf.h'
void Error_Handler(void);
void SystemClock_Config(void);
void Startup_Sequence(void);
UART_HandleTypeDef UartHandle;
__IO ITStatus UartReady = RESET;
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *UartHandle) {
 UartReady = SET;
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle) {
 UartReady = SET;
}
void USART1_IRQHandler(void) {
 HAL_UART_IRQHandler(&UartHandle);
}
int main(void) {
HAL_Init();
 SystemInit();
 SystemClock_Config();
 GPIO_InitTypeDef GPIO_InitStruct;
 // Enable GPIO and USART1 clocks.
 __HAL_RCC_GPIOA_CLK_ENABLE();
 __HAL_RCC_GPIOB_CLK_ENABLE();
 __HAL_RCC_USART1_CLK_ENABLE();
 // Setup LED pin
 GPIO_InitStruct.Pin = GPIO_PIN_15;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 // Setup UART TX Pin
 GPIO_InitStruct.Pin = GPIO_PIN_9;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_PULLUP;
 GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 //Setup UART RX Pin
 GPIO_InitStruct.Pin = GPIO_PIN_10;
 GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
 GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 HAL_Delay(1000);
 //Setup UART Instance
 UartHandle.Instance = USART1;
 UartHandle.Init.BaudRate = 9600;
 UartHandle.Init.WordLength = UART_WORDLENGTH_8B;
 UartHandle.Init.StopBits = UART_STOPBITS_1;
 UartHandle.Init.Parity = UART_PARITY_NONE;
 UartHandle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 UartHandle.Init.Mode = UART_MODE_TX_RX;
 //Error handling
 if(HAL_UART_DeInit(&UartHandle) != HAL_OK) {
 Error_Handler();
 }
 if(HAL_UART_Init(&UartHandle) != HAL_OK) {
 Error_Handler();
 }
 HAL_NVIC_SetPriority(USART1_IRQn, 0, 1);
 HAL_NVIC_EnableIRQ(USART1_IRQn);
 uint8_t msg[] = '';
 Startup_Sequence();
 while(1) {
 if(HAL_UART_Transmit_IT(&UartHandle, &msg, sizeof(msg))!= HAL_OK) {
 Error_Handler();
 }
 while (UartReady != SET){}
 UartReady = RESET;
 if(HAL_UART_Receive_IT(&UartHandle, &msg, sizeof(msg)) != HAL_OK) {
 Error_Handler();
 }
 while (UartReady != SET){}
 UartReady = RESET;
 }
}
/**
 * Blinks external LED (PIN B15) if error encountered.
 */
void Error_Handler(void) {
 while(1) {
 HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_15);
 HAL_Delay(1000);
 }
}
void Startup_Sequence(void) {
 int i;
 for(i=1;i<10; i++) {
 HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_15);
 HAL_Delay(1000 * (1.0/i));
 }
 HAL_GPIO_WritePin(GPIOB, GPIO_PIN_15, GPIO_PIN_RESET);
}
void SystemClock_Config(void) {
 RCC_ClkInitTypeDef clkinitstruct = {0};
 RCC_OscInitTypeDef oscinitstruct = {0};
 oscinitstruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
 oscinitstruct.HSEState = RCC_HSE_ON;
 oscinitstruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
 oscinitstruct.PLL.PLLState = RCC_PLL_ON;
 oscinitstruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 oscinitstruct.PLL.PLLMUL = RCC_PLL_MUL9;
 if (HAL_RCC_OscConfig(&oscinitstruct)!= HAL_OK) {
 while(1);
 }
 clkinitstruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2);
 clkinitstruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 clkinitstruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 clkinitstruct.APB2CLKDivider = RCC_HCLK_DIV1;
 clkinitstruct.APB1CLKDivider = RCC_HCLK_DIV2;
 if (HAL_RCC_ClockConfig(&clkinitstruct, FLASH_LATENCY_2)!= HAL_OK) {
 while(1);
 }
}
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I am having problems with this however. Characters are being lost, I think because of an overrun. Below is an image of transmitted data vs received.

http://i.imgur.com/GTupBhK.png

So what must I change in my code to prevent an overrun?

Many thanks.