Next you can find two steps to solve the issue. Follow them step by step in the order they're indicated.
After each step try to connect with Isabel 6 or the e-applications of the government.
Once the problem is solved, you do not need to proceed with the subsequent step.
Close all open Internet Explorer windows or restart your computer.
Retry to access Isabel or one of the e-applications of FOD Financiën/SPF Finances.
When prompted, select the correct certificate.
You can remove a certificate from your computer if it is not in use anymore.
If you've selected the correct certificate and you try to access one of the e-applications of FOD Financiën/SPF Finances, we advise you to contact them in order to verify if your Isabel-card is correctly registered for their services.