The phrase "looking forward to your cooperation" is correct and usable in written English. It expresses anticipation of a future collaboration and can be used when writing to someone you know who is likely willing to cooperate with you. For example: "I am excited to start this new project and I'm looking forward to your cooperation in the coming months."
I look forward to your cooperation, and I look forward to huge consultancy check from the RIAA.
I look forward to your cooperation when we come to those two challenging weeks ahead of us.
Start looking forward to your big celebration.
Nanjing Normal University is looking forward to your presence.
You may rest assured that we have the best interests of 'Insights into Imaging' and the ESR at heart, and we look forward to your support and continued cooperation.
I look forward to your prompt attention and cooperation.
I look forward to your joining us.
I'll look forward to your company.
I look forward to your Martin Luther King.
I look forward to your submissions.
I look forward to your questions.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK