Why is PayU causing checkout errors in my Colombian online store?

[Rosario531]

Hello Shopify team.
I've built Shopify store in Colombia and integrated PayU as payment provider.
But now it has issues in checkout step with error message-"An error occurred while processing your payment. Please try again or use a different payment method."

What is the reason of this issue and how to fix it.
I look forward to hearing from you soon.
Best, Rosario