Custom stamp not stamping when selected

I have created a custom stamp to sign letters and complete letters ie not just a signature of my name but other info too. Every time I select it it appears "greyed out" on the page and then I try to place it and it doesn't go. I have to click over and over again and then maybe it will agree to place it somewhere on the page at which point I need to move it and align it etc. How do I fix this?  why can I select a different stamp and it immediately stamps where I click but this won't? 

Thanks