USB ADC DMA not working in STM32L476RG

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I am using DMA in circular mode for ADC and transmitting data through USART. But now I wanted more speed so I thought of using USB. 

I am able to send a string using USB. But when I enable DMA in circular mode and turn on the "Continuous conversions" and " DMA Continuous Request". The USB port doesn't show up.

What could be the issue?

[AKhot.1]

This is my clock settings 

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This is my DMA settings