Sedum "Autumn Joy" problem

[new england gal]

I have a sedum "Autmn Joy" and something is killing it. It has made the stalks squishy about mid-way up. Would this be a borer, a fungus, or what? I've had sedums in my other gardens and never had a problem. Thia is a completely new garden and new plantings.

I appreciate everyone's input on this.

[rastapasta]

I dunno, but I have just planted a different species of sedum, but this is what I got from here:

"If grown in the partial shade garden, S. 'Autumn Joy' becomes leggy and flops over. This also can be an indication that it is time to divide the plant".

Also, are you overwatering it?