Cannot create checkpoint on cluster, access denied (solved, but request for comment)

Hi, we have a 3 node hyper-v cluster windows server 2012 R2. They have shared iscsi disks. When I want to create a checkpoint, I get the following:

Error (12700)
VMM cannot complete the host operation on the ams1svw011.wessanen.local server because of the error: Checkpoint operation for 'AMS1SAW029' failed. (Virtual machine ID 8A857DA6-6534-4631-8315-CD14488F79CC)

'AMS1SAW029' cannot create the storage required for the checkpoint using disk C:\ClusterStorage\Volume7\AMS1SAW029_disk_1.vhdx: General access denied error (0x80070005). (Virtual machine ID 8A857DA6-6534-4631-8315-CD14488F79CC)
Unknown error (0x8001)

Recommended Action
Resolve the host issue and then try the operation again.

Je suis er even nie