WinCC flex Application doesnot open

Greetings
i do have and application the is a Siemens PLC and HMI configured by Winccflex

the application is integrated , when i want to open the HMI Application to do some changes it not working and i have an error massage that says that the (.hmi) and the (.ldf) is not match

what is the mean of this error massage and how i can overcome this problem ?

kindly advice

is the valid user to make changes

Greetings
yes it is valid user approach
many thanks