There may be several reasons why the Weihai Bank credit card application signature cannot be written:

1. Technical problems: During the credit card application process, there may be technical problems that prevent the electronic signature. Complete the signature on the application form. This may be caused by network connection issues, browser compatibility issues, or system failures on the application platform.

2. Equipment problems: If you are using an electronic device to complete the credit card application, the signature may not be performed normally due to incorrect input settings of the device or device hardware problems. This could include a faulty keyboard, touchscreen issue, or mouse issue, among others.

3. Signature skills: Signing requires certain skills and experience. If you are not familiar with how to write a signature or lack the flexibility of handwriting, the signature may not be completed or does not meet the requirements.

4. Platform requirements: Weihai Bank may have specific requirements for signatures on the application form, such as specific signature areas, signature style regulations, etc. If you do not follow the requirements, your signature may not be completed. If you encounter problems unable to complete the signature, it is recommended that you first check whether there are technical or equipment problems, such as confirming that the network connection is normal and trying to use a different device or browser to apply. In addition, it is also recommended that you contact the customer service department of Weihai Bank to explain the problem and seek their help and guidance. They will be able to provide more specific reasons and solutions.