Question: Integration error, "wrong number or type of arguments"

I have an equation on paper that I am trying to rewrite in Maple for plotting purposes. 

Because the equation is large, I split it up in different parts, "frontcoeff", "cosCterm", etc. Ultimately I want an equation "u" which is a function of (r,theta,t) and is composed of a summation over "k" and "m". 

Image 1:

I then get the following error:

Image 2:


Any ideas?


Thank you!

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