Question: Don't know the error code for system of ODEs

Good day sirs,

I am having trouble identifying the error in the system of first-order ODEs. It gives the error code of

" Error, (in dsolve/numeric/process_input) received more than one indication of the dependent vars [theta[1](t), theta[2](t), theta[3](t), theta[4](t), theta[5](t), theta[6](t), theta[7](t), theta[8](t), theta[9](t)].

The document is attached below.

Thank you

Please Wait...